3. Match the following
Frame 1 ( for testing pre-requisite)
Simple closed curve
A closed curve that is
not simple
Simple curve that is
not closed
Not a simple curve
4. Frame 2
A simple closed curve made up of only line
segments is called a polygon.
Eg:
These curves are polygons. This curve is not a polygon.
Given here are some figures.
Identify the polygons.
5. Frame 3
These are polygons
We can name the polygons according to the number of sides( or
no.of vertices) as they have.
no.of sides classification figure
3 Triangle
4 Quadrilateral
5 Pentagon
6 - sided polygon is hexagon.
7 -sided polygon is heptagon.
Octagon is apoygon of 8 sides.
9 sided polygon is nonagon.
Decagon is a polygon of 10 sides.
6. a) b)
Name the polygons
a)
Frame 4
Hexagon octagon
A diagonal can be defined as a line segment connecting two non-
consecutive vertices of a polygon.
7. a) Draw all the diagonals of a pentagon ?
c
D
B
E
D
B
C
A
We can draw only two diagonals ( BD & AC) for a quadrilateral.
F
b) is DF a diagonal ?
8. b) DF is not a diagonal.
Convex polygons: polygons that are convex have no portions of
their diagonals in their exteriors.
Concave polygons: polygons that are concave have portions of
their diagonals in their exterior.
Frame 5
These polygons are convex polygons.
9. This polygon is a concave
polygon.
Here are some polygons.classify them as concave and convex
polygons
10. Frame 6
These three are convex
polygons.others are concave
polygons.
Regular polygons : A regular polygon has both equal sides and
angles.
Irregular polygons: The polygons that are not regular is called irregular
poygons.
These polygons are regular polygons.
This is an irregular polygon.
11. .
Is a rectangle a regular polygon?
Is an equilateral triangle a regular polygon ?
Frame 7
A rectangle is not a regular polygon.
An equilateral triangle is a regular polygon.
Angle sum property:we have used this property to find the angle sum
of apolygon.For this we first have to see the number of sides of a
polygon,then subtract 2 from it and multiply the result by 180 to find its
total angle sum.
That is , a quadrilateral has 4 sides .
Then sum of the angles of a quadrilateral is 4-2=2 then 2 multiplied by
180= 360.
What is the sum of angles of a pentagon ? &
Also find the sum of angles of a hexagon.
12. Frame 8
The sum of the angles of a pentagon is 5-2=3 then 3 multiplied by 180= 540.
The sum of the angles of a hexagon is 6-2=4 then 4 multiplied by 180= 720 .
For a regular polygon interior angle plus exterior angle is always 180
.
That is ,
A B
A+B =180
Find the measure of angle B.
B
30
13. The measure of angle B is 180-30=150 .
Frame 9
Sum of the measure of exterior angles of any polygon is always equal to
360 .
120
150
150+B+120=360
So B=360-270=90B
Therefore the measure of the angle B is 90
50
90
110
A
Find the measure of angle B
14. The measure of the angle B is 110+90+50+ B=360
Then B=360-250=110.
Frame 10
Trapezium: Trapezium is a quadrilateral with a pair of parallel sides.
This is not a trapezium
This is a trapezium
Here are some polygons .Identify the trapezium from it
15. Frame 11
Thse are Trapeziums.
Kite : kite is a speacial type of quadrilateral. It has 4 sides.also
there are exactly two distinct consecutive pairs of sides of equal
length.
This is not kite. This is a kite.
17. Not aparallelogram
Parallelogram : A parallelogram is a quadrilateral whose
opposite sides are parallel.
A
parallelogram
A D
B C
Identify the parallel sides of the parallelogram
18. Frame 13
AB and CD are parallel sides.
BC and CD are second pair of parallel sides
The opposite angles of a parallelogram are of equal measure.
BA
110 70
Find the measure of angle A and B
The measure of angle A is 70.
The measure of angle B is 110.
Frame 14
19. This is a rhombus.
State whether true or false
1.All squares are rhombuses.
2. All kites are rhombuses.
3. All rhombuses are parallelograms.
Rhombus : A rhombus is a quadrilateral with equal sides. It has all
the properties of a parallelogram and also that of a kite.
This is a kite.
Frame 15
All squares are rhombuses.
All kites are rhombuses.
All rhombuses are parallelograms
20. Rectangle : A rectangle is a parallelogram with equal
angles. Being a parallelogram it has opposite sides of equal
length.
Q23: A Rectangle is a ............
quadrilateral.
A ractangle is a convex quadrilateral
Frame 16
Square : A Square is a rectangle with
equal sides.
21. Frame 17
1. All squares are not
parallelograms.
2. All squares are trapeziums.
3. All rectangles are squares.
1. False.
2. True.
3. False.
State whether true or false
22. Match the following
Frame 1 ( for testing pre-requisite)
Simple closed curve
A closed curve that is
not simple
Simple curve that is
not closed
Not a simple curve
