Angle Facts
Objectives:
F Grade Express fractions of full turns in degrees
and vice versa
Recognise acute, obtuse, reflex and right angles
Estimate angles and measure them accurately
Use properties of angles at a point and angles
on a straight line
Understand the terms ‘perpendicular lines and
‘parallel lines’
D Grade Recognise corresponding angles and alternate angles
Angle Facts
Define: Perpendicular Lines
Define: Parallel
Two lines at right angles (90o) to each
other
Straight lines that are always the same
distance apart and never meet
Angle Facts
Starter:
Name these angles:
Acute
Reflex
Right Angle
Obtuse
90
90
90
90
Vertical
Horizontal
360o
1
360o
2
360o
3
360o
4
360o
Angles at a Point
a
b
c
d
Angles at a point add to 360o
Angle a + b + c + d = 3600
Angles at a Point
75o
85o
80o
a
Example: Find angle a.
90 90
90 90
360o
Angle a = 360 - (85 + 75 + 80)
= 360 - 240 = 120o
85
75
80
+
240
Angles at a Point
a
b
c
d
Opposite Angles are equal
Angle a + b = 1800 because they form a
straight line
Angle c + d = 1800 because they form a
straight line
Angle c + b = 1800 because they form a
straight line
Angle d + a = 1800 because they form a
straight line
So a = c and b = d
Angles at a Point
Horizontal line
Oblique line
a
b
Angles a + b = 180o
70o
b
Angle b = 180 – 70 = 110o
x
35o
Angle x = 180 – 35 = 145o
90 90
Angles on a straight line add to 180o
180o
Angles on a Line
Angle Facts
Now do these:
f
g
g
g
2h
h
60o
45o 120o
110o
35o
a
b
22o
116o
c
d
e
135o
80o
148o
i
a = 180 – 35 = 145o
b = 180 – (22+90) = 68o
Opposite angles are equal
So c = 116o
d = 180 – 116 = 64o
e = 360 – (135+80) = 145o
f = 360 – (45+120+110)
f = 360 - 275 = 85o
3g = 360 – (90+60) = 210
g = 70
i = 180 - 148 = 32o
3h = 180 – i = 148
h = 49.3
.
Parallel lines
remain the same
distance apart.
Transversal
Draw a pair of parallel
lines with a transversal
and measure the 8 angles.
Vertically opposite angles are equal.
Corresponding angles are equal.
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
Draw a pair of parallel
lines with a transversal
and measure the 8 angles.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
Draw a pair of parallel
lines with a transversal
and measure the 8 angles.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Angles between Parallel Lines
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
a
d c
e
g
h
f
Name an angle
corresponding to the
marked angle.
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
c
e
g
h
f
Name an angle
corresponding to the
marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
c
h g
d
f
Name an angle
corresponding to the
marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
e
h g
d
f
Name an angle
corresponding to the
marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
e
h g
d
f
Name an angle alternate
to the marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
e
h g
d c
Name an angle alternate
to the marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
e
h g
d
c
Name an angle interior
to the marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
Parallel lines
remain the same
distance apart.
Transversal
a b
e
h g
d c
Name an angle interior
to the marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
a
f
e
h
g
d
c
Name an angle
corresponding to the
marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
a
f
e
b g
d
c
Name an angle alternate
to the marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
h
f
e
b g
d
c
Name an angle interior
to the marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
h
f
e
b
g
d
c
Name in order, the
angles that are
alternate, interior and
corresponding to the
marked angle.
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Angles between Parallel Lines
a
f
e
h
g
d
c
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Name in order, the
angles that are
alternate, interior and
corresponding to the
marked angle.
Angles between Parallel Lines
x
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Finding unknown angles
100o Find the
unknown
angles stating
reasons, from
the list below.
y
z
60o
 x =
 y =
 z =
80o Int. s
60o vert.opp. s
120o Int. s
Angles between Parallel Lines
x
Vertically opposite angles are equal. vert.opp. s
Corresponding angles are equal. corr. s
Alternate angles are equal. alt. s
Interior angles sum to 180o .(Supplementary) Int. s
Finding unknown angles
105o
Find the
unknown
angles stating
reasons, from
the list below.
y
z
 x =
 y =
 z =
105o corr. s
55o alt. s
125o Int. s
55o
Angles between Parallel Lines
x
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Finding unknown angles
95o Find the
unknown
angles stating
reasons, from
the list below.
y
 x =
 y =
85o Int. s
120o Int. s
60o
Unknown
angles in
quadrilaterals
and other
figures can be
found using
these
properties.
Angles between Parallel Lines
x
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Finding unknown angles
Find the
unknown
angles stating
reasons, from
the list below.
y
55o
z
 x =
 y =
 z =
What does this tell you about parallelograms?
125o Int. s
125o
55o Int. s
55o
125o Int. s
125o
Unknown
angles in
quadrilaterals
and other
figures can be
found using
these
properties.
Angles between Parallel Lines
70o
a
Vertically opposite angles are equal.
Corresponding angles are equal.
Alternate angles are equal.
Interior angles sum to 180o .(Supplementary)
Find the
unknown
angles stating
reasons, from
the list below.
There may be
more than one
reason.
58o vert.opp. s
32o s in tri
58o
32o alt. s
b
d
c
Angle sum of a triangle (180o)
Angle on a line sum to (180o)
58o s on line
e 58o corr. s
52o s at a point
f
g
h
Base angles isosceles triangle equal.
64o isos tri
 a =
 b =
 c =
 d =
 e =
 f =
 g =
 h = 64o isos tri
Angles at a point sum to 360o
Mixing it!
Angles between Parallel Lines
Angle Facts
Now do these:
65o
p
99o
77o
38o
54o
48o
35o
z
130o
y
x
w
t u
s
r
q
v
Corresponding angles
p = 65o
Alternate angles
q = 38o
Corresponding angles
r = 77o
Opposite angles (with r)
or Alternate angles with 77o
s = 77o
t = 99o
v = 54o
u = 81o
w = 126o
x = 130o
y = 130o
z = 35o + 48o = 83o

angle facts.ppt angle facts angle facts angle facts

  • 1.
    Angle Facts Objectives: F GradeExpress fractions of full turns in degrees and vice versa Recognise acute, obtuse, reflex and right angles Estimate angles and measure them accurately Use properties of angles at a point and angles on a straight line Understand the terms ‘perpendicular lines and ‘parallel lines’ D Grade Recognise corresponding angles and alternate angles
  • 2.
    Angle Facts Define: PerpendicularLines Define: Parallel Two lines at right angles (90o) to each other Straight lines that are always the same distance apart and never meet
  • 3.
    Angle Facts Starter: Name theseangles: Acute Reflex Right Angle Obtuse
  • 4.
  • 5.
    a b c d Angles at apoint add to 360o Angle a + b + c + d = 3600 Angles at a Point
  • 6.
    75o 85o 80o a Example: Find anglea. 90 90 90 90 360o Angle a = 360 - (85 + 75 + 80) = 360 - 240 = 120o 85 75 80 + 240 Angles at a Point
  • 7.
    a b c d Opposite Angles areequal Angle a + b = 1800 because they form a straight line Angle c + d = 1800 because they form a straight line Angle c + b = 1800 because they form a straight line Angle d + a = 1800 because they form a straight line So a = c and b = d Angles at a Point
  • 8.
    Horizontal line Oblique line a b Anglesa + b = 180o 70o b Angle b = 180 – 70 = 110o x 35o Angle x = 180 – 35 = 145o 90 90 Angles on a straight line add to 180o 180o Angles on a Line
  • 9.
    Angle Facts Now dothese: f g g g 2h h 60o 45o 120o 110o 35o a b 22o 116o c d e 135o 80o 148o i a = 180 – 35 = 145o b = 180 – (22+90) = 68o Opposite angles are equal So c = 116o d = 180 – 116 = 64o e = 360 – (135+80) = 145o f = 360 – (45+120+110) f = 360 - 275 = 85o 3g = 360 – (90+60) = 210 g = 70 i = 180 - 148 = 32o 3h = 180 – i = 148 h = 49.3 .
  • 10.
    Parallel lines remain thesame distance apart. Transversal Draw a pair of parallel lines with a transversal and measure the 8 angles. Vertically opposite angles are equal. Corresponding angles are equal. Angles between Parallel Lines
  • 11.
    Parallel lines remain thesame distance apart. Transversal Draw a pair of parallel lines with a transversal and measure the 8 angles. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Angles between Parallel Lines
  • 12.
    Parallel lines remain thesame distance apart. Transversal Draw a pair of parallel lines with a transversal and measure the 8 angles. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 13.
  • 14.
  • 15.
    Parallel lines remain thesame distance apart. Transversal Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) a d c e g h f Name an angle corresponding to the marked angle. Angles between Parallel Lines
  • 16.
    Parallel lines remain thesame distance apart. Transversal a b c e g h f Name an angle corresponding to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 17.
    Parallel lines remain thesame distance apart. Transversal a b c h g d f Name an angle corresponding to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 18.
    Parallel lines remain thesame distance apart. Transversal a b e h g d f Name an angle corresponding to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 19.
    Parallel lines remain thesame distance apart. Transversal a b e h g d f Name an angle alternate to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 20.
    Parallel lines remain thesame distance apart. Transversal a b e h g d c Name an angle alternate to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 21.
    Parallel lines remain thesame distance apart. Transversal a b e h g d c Name an angle interior to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 22.
    Parallel lines remain thesame distance apart. Transversal a b e h g d c Name an angle interior to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 23.
    a f e h g d c Name an angle correspondingto the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 24.
    a f e b g d c Name anangle alternate to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 25.
    h f e b g d c Name anangle interior to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 26.
    h f e b g d c Name in order,the angles that are alternate, interior and corresponding to the marked angle. Vertically opposite angles are equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Angles between Parallel Lines
  • 27.
    a f e h g d c Vertically opposite anglesare equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Name in order, the angles that are alternate, interior and corresponding to the marked angle. Angles between Parallel Lines
  • 28.
    x Vertically opposite anglesare equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Finding unknown angles 100o Find the unknown angles stating reasons, from the list below. y z 60o  x =  y =  z = 80o Int. s 60o vert.opp. s 120o Int. s Angles between Parallel Lines
  • 29.
    x Vertically opposite anglesare equal. vert.opp. s Corresponding angles are equal. corr. s Alternate angles are equal. alt. s Interior angles sum to 180o .(Supplementary) Int. s Finding unknown angles 105o Find the unknown angles stating reasons, from the list below. y z  x =  y =  z = 105o corr. s 55o alt. s 125o Int. s 55o Angles between Parallel Lines
  • 30.
    x Vertically opposite anglesare equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Finding unknown angles 95o Find the unknown angles stating reasons, from the list below. y  x =  y = 85o Int. s 120o Int. s 60o Unknown angles in quadrilaterals and other figures can be found using these properties. Angles between Parallel Lines
  • 31.
    x Vertically opposite anglesare equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Finding unknown angles Find the unknown angles stating reasons, from the list below. y 55o z  x =  y =  z = What does this tell you about parallelograms? 125o Int. s 125o 55o Int. s 55o 125o Int. s 125o Unknown angles in quadrilaterals and other figures can be found using these properties. Angles between Parallel Lines
  • 32.
    70o a Vertically opposite anglesare equal. Corresponding angles are equal. Alternate angles are equal. Interior angles sum to 180o .(Supplementary) Find the unknown angles stating reasons, from the list below. There may be more than one reason. 58o vert.opp. s 32o s in tri 58o 32o alt. s b d c Angle sum of a triangle (180o) Angle on a line sum to (180o) 58o s on line e 58o corr. s 52o s at a point f g h Base angles isosceles triangle equal. 64o isos tri  a =  b =  c =  d =  e =  f =  g =  h = 64o isos tri Angles at a point sum to 360o Mixing it! Angles between Parallel Lines
  • 33.
    Angle Facts Now dothese: 65o p 99o 77o 38o 54o 48o 35o z 130o y x w t u s r q v Corresponding angles p = 65o Alternate angles q = 38o Corresponding angles r = 77o Opposite angles (with r) or Alternate angles with 77o s = 77o t = 99o v = 54o u = 81o w = 126o x = 130o y = 130o z = 35o + 48o = 83o