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5. Draw and name the following polygons. ANGLES AND THEIR MEASUREMENT
a. Polygon with three sides. c. Polygon with seven sides.
b. Polygon with five sides. In our daily life, we come across physical objects having two arms, joined together at a common point. For
example, the hands of a clock and the two arms of a divider.
6. Answer the following. These arms are hinged at a point, as shown in the figures given below.
a. How many lines can you draw passing through two points?
b. How many lines can you draw through a single point?
c. Three points, A, Band C, are collinear. Depict this statement through an appropriate figure.

7. Identify the linear and curvilinear boundaries of the following figures.

Clock Divider
(i) (ii)
It can be said that each pair of arms forms an angle at its joint.

In geometry, we define the angle as under.

ANGLE The figure formed by two rays with the same initial point is called an angle.

8. Draw two figures each to depict the following. The common initial point is known as the vertex of the angle, and the rays forming the angle are called
a. A closed figure. b. An open figure. its arms or sides.

9. Give one example from daily life to depict the following. In the figure given below, two rays OA and OB with a common initial point O form an angle. We name
a. Plane surface. b. Curved surface. this angle as √AOB or √BOA, keeping the name of the vertex in the middle.
c. Linear boundary. d. Curved boundary.
e. Partly linear and partly curved boundary. B

O A C
We read it as angle AOB or angle BOA. The symbol √ stands for angle.

We can simply call it √O. 1 B
A 2
When there are more than one angle in a figure, we label them 1, 2, 3, etc.,
and call them √l, √2, √3, etc.
D
Thus, in the adjoining figure, √ABC = √l and √BAD = √2.
Two line segments with a common initial point also form an angle, as shown in the adjoining figure.
Actually speaking, OA and OB are parts of the rays OA and OB.