Identifying Angles in a Figure
1. What is an angle?
An angle is the amount of turning between two lines meeting at a point.
2. How are angles formed?
When 2 lines meet at a point, they form an angle at that point.
3. How do we denote angles?
We denote angle using the symbol ∠.
1. Ali bends a straw as below. Mark the angle formed by it.
The bent straw (presented by the blue lines) forms an angle as marked by the red turning.
2. Following are examples of angles on objects we see everyday.
On each object, the angles are marked by the yellow turning.
3. Here are some pairs of pencils placed in pairs.
Which of these pairs form angles?
Pairs A, C and D form angles.
4. Study the angles below.
a. Which angle is the smallest?
b. Which angle is the greatest?
c. Arrange the angles in order, beginning with the smallest.
a. The lines forming Angle Y have the smallest turning.
So, ∠Y is the smallest angle.
So, ∠Y is the smallest angle.
b. The lines forming Angle X have the greatest turning.
So, ∠X is the greatest angle.
So, ∠X is the greatest angle.
c. Beginning with the smallest, the angles can be arranged as below:
∠Y, ∠Z, ∠X
∠Y, ∠Z, ∠X
5. Rayan makes some shapes as shown below.
How many sides and angles does each shape have?
Shape A has 3 sides and 3 angles.
Shape B has 4 sides and 4 angles.
Shape C has 5 sides and 5 angles.
Shape D has 6 sides and 6 angles.
Shape B has 4 sides and 4 angles.
Shape C has 5 sides and 5 angles.
Shape D has 6 sides and 6 angles.