8. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to
is congruent to
||| is similar to
therefore
because
9. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to X
XY is produced to A
Y A
is congruent to
||| is similar to
therefore
because
10. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to B X
XY is produced to A
Y A
is congruent to
YX is produced to B
||| is similar to
therefore
because
11. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to B X
XY is produced to A
Y A
is congruent to
YX is produced to B
||| is similar to
foot – the base or the bottom
therefore
because
12. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to B X
XY is produced to A
Y A
is congruent to
YX is produced to B
||| is similar to
foot – the base or the bottom
therefore A
B B is the foot of the perpendicular
because
D C
13. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to B X
XY is produced to A
Y A
is congruent to
YX is produced to B
||| is similar to
foot – the base or the bottom
therefore A
B B is the foot of the perpendicular
because
D C
collinear – the points lie on the same line
14. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to B X
XY is produced to A
Y A
is congruent to
YX is produced to B
||| is similar to
foot – the base or the bottom
therefore A
B B is the foot of the perpendicular
because
D C
collinear – the points lie on the same line
concurrent – the lines intersect at the same
point
15. Euclidean Geometry
Geometry Definitions Terminology
Notation produced – the line is extended
|| is parallel to
is perpendicular to B X
XY is produced to A
Y A
is congruent to
YX is produced to B
||| is similar to
foot – the base or the bottom
therefore A
B B is the foot of the perpendicular
because
D C
collinear – the points lie on the same line
concurrent – the lines intersect at the same
point
transversal – a line that cuts two(or more)
other lines
17. Naming Conventions
Angles and Polygons are named in cyclic order
ABC or ABC ˆ
A
If no ambiguity
B C
B or B
ˆ
18. Naming Conventions
Angles and Polygons are named in cyclic order
ABC or ABC ˆ P
A
If no ambiguity V VPQT or QPVT
B C
ˆ
B or B
Q or QTVP etc
T
19. Naming Conventions
Angles and Polygons are named in cyclic order
ABC or ABC ˆ P
A
If no ambiguity V VPQT or QPVT
B C
ˆ
B or B
Q or QTVP etc
T
Parallel Lines are named in corresponding order
20. Naming Conventions
Angles and Polygons are named in cyclic order
ABC or ABC ˆ P
A
If no ambiguity V VPQT or QPVT
B C
ˆ
B or B
Q or QTVP etc
T
Parallel Lines are named in corresponding order
B
D
AB||CD
A
C
21. Naming Conventions
Angles and Polygons are named in cyclic order
ABC or ABC ˆ P
A
If no ambiguity V VPQT or QPVT
B C
ˆ
B or B
Q or QTVP etc
T
Parallel Lines are named in corresponding order
B
D
AB||CD
A
C
Equal Lines are marked with the same symbol
22. Naming Conventions
Angles and Polygons are named in cyclic order
ABC or ABC ˆ P
A
If no ambiguity V VPQT or QPVT
B C
ˆ
B or B
Q or QTVP etc
T
Parallel Lines are named in corresponding order
B
D
AB||CD
A
C
Equal Lines are marked with the same symbol
Q R
PQ = SR
P PS = QR
S
24. Constructing Proofs
When constructing a proof, any line that you state must be one of the
following;
1. Given information, do not assume information is given, e.g. if you
are told two sides are of a triangle are equal don’t assume it is
isosceles, state that it is isosceles because two sides are equal.
25. Constructing Proofs
When constructing a proof, any line that you state must be one of the
following;
1. Given information, do not assume information is given, e.g. if you
are told two sides are of a triangle are equal don’t assume it is
isosceles, state that it is isosceles because two sides are equal.
2. Construction of new lines, state clearly your construction so that
anyone reading your proof could recreate the construction.
26. Constructing Proofs
When constructing a proof, any line that you state must be one of the
following;
1. Given information, do not assume information is given, e.g. if you
are told two sides are of a triangle are equal don’t assume it is
isosceles, state that it is isosceles because two sides are equal.
2. Construction of new lines, state clearly your construction so that
anyone reading your proof could recreate the construction.
3. A recognised geometrical theorem (or assumption), any theorem
you are using must be explicitly stated, whether it is in the algebraic
statement or the reason itself.
27. Constructing Proofs
When constructing a proof, any line that you state must be one of the
following;
1. Given information, do not assume information is given, e.g. if you
are told two sides are of a triangle are equal don’t assume it is
isosceles, state that it is isosceles because two sides are equal.
2. Construction of new lines, state clearly your construction so that
anyone reading your proof could recreate the construction.
3. A recognised geometrical theorem (or assumption), any theorem
you are using must be explicitly stated, whether it is in the algebraic
statement or the reason itself.
e.g. A 25 120 180 sum 180
28. Constructing Proofs
When constructing a proof, any line that you state must be one of the
following;
1. Given information, do not assume information is given, e.g. if you
are told two sides are of a triangle are equal don’t assume it is
isosceles, state that it is isosceles because two sides are equal.
2. Construction of new lines, state clearly your construction so that
anyone reading your proof could recreate the construction.
3. A recognised geometrical theorem (or assumption), any theorem
you are using must be explicitly stated, whether it is in the algebraic
statement or the reason itself.
e.g. A 25 120 180 sum 180
Your reasoning should be clear and concise
29. Constructing Proofs
When constructing a proof, any line that you state must be one of the
following;
1. Given information, do not assume information is given, e.g. if you
are told two sides are of a triangle are equal don’t assume it is
isosceles, state that it is isosceles because two sides are equal.
2. Construction of new lines, state clearly your construction so that
anyone reading your proof could recreate the construction.
3. A recognised geometrical theorem (or assumption), any theorem
you are using must be explicitly stated, whether it is in the algebraic
statement or the reason itself.
e.g. A 25 120 180 sum 180
Your reasoning should be clear and concise
4. Any working out that follows from lines already stated.
32. Angle Theorems
D Angles in a straight line add up to 180
x 30
A B C
33. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C
34. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
35. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
36. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39
37. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39 3x 39 vertically opposite' s are
38. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39 3x 39 vertically opposite' s are
x 13
39. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39 3x 39 vertically opposite' s are
x 13
Angles about a point equal 360
40. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39 3x 39 vertically opposite' s are
x 13
150 Angles about a point equal 360
15
y120
41. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39 3x 39 vertically opposite' s are
x 13
150 Angles about a point equal 360
15
y120 y 15 150 120 360 revolution 360
42. Angle Theorems
D Angles in a straight line add up to 180
A
x 30 x 30 180 straight ABC 180
B C x 150
Vertically opposite angles are equal
3x 39 3x 39 vertically opposite' s are
x 13
150 Angles about a point equal 360
15
y120 y 15 150 120 360 revolution 360
y 75
47. Parallel Line Theorems
Alternate angles (Z) are equal a bd
c f
c f alternate' s , || lines e h
d e g
Corresponding angles (F) are equal
48. Parallel Line Theorems
Alternate angles (Z) are equal a bd
c f
c f alternate' s , || lines e h
d e g
Corresponding angles (F) are equal
ae corresponding' s , || lines
49. Parallel Line Theorems
Alternate angles (Z) are equal a bd
c f
c f alternate' s , || lines e h
d e g
Corresponding angles (F) are equal
ae corresponding' s , || lines
b f
cg
d h
50. Parallel Line Theorems
Alternate angles (Z) are equal a bd
c f
c f alternate' s , || lines e h
d e g
Corresponding angles (F) are equal
ae corresponding' s , || lines
b f
cg
d h
Cointerior angles (C) are supplementary
51. Parallel Line Theorems
Alternate angles (Z) are equal a bd
c f
c f alternate' s , || lines e h
d e g
Corresponding angles (F) are equal
ae corresponding' s , || lines
b f
cg
d h
Cointerior angles (C) are supplementary
c e 180 cointerior' s 180, || lines
52. Parallel Line Theorems
Alternate angles (Z) are equal a bd
c f
c f alternate' s , || lines e h
d e g
Corresponding angles (F) are equal
ae corresponding' s , || lines
b f
cg
d h
Cointerior angles (C) are supplementary
c e 180 cointerior' s 180, || lines
d f 180
54. A B
e.g.
120
P
y
x 65
C Q D
x 65 180 straight CQD 180
55. A B
e.g.
120
P
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
56. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
57. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
XPQ 65 alternate' s , XY || CQ
58. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
XPQ 65 alternate' s , XY || CQ
XPB 120 180 cointerior' s 180 , AB || XY
59. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
XPQ 65 alternate' s , XY || CQ
XPB 120 180 cointerior' s 180 , AB || XY
XPB 60
60. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
XPQ 65 alternate' s , XY || CQ
XPB 120 180 cointerior' s 180 , AB || XY
XPB 60
BPQ XPQ XPB common
61. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
XPQ 65 alternate' s , XY || CQ
XPB 120 180 cointerior' s 180 , AB || XY
XPB 60
BPQ XPQ XPB common
y 65 60
y 125
62. A B
e.g.
120
X P Y
y
x 65
C Q D
x 65 180 straight CQD 180
x 115
Construct XY||CD passing through P
Book 2
XPQ 65 alternate' s , XY || CQ Exercise 8A;
XPB 120 180 cointerior' s 180 , AB || XY
1cfh, 2bdeh,
3bd, 5bcf,
XPB 60
6bef, 10bd,
BPQ XPQ XPB common 11b, 12bc,
y 65 60 13ad, 14, 15
y 125