## Chapter 16 – Quadrilaterals

## Practice set 37

**Observe the figures below and find out their names.**

**1.**

**Ans: **Pentagon (5 sides)

**2.**

**Ans: **Hexagon (6 sides)

**3.**

**Ans: **Heptagon (7 sides)

**4.**

**Ans: **Octagon (8 sides)

## Practice set 38

**1. Draw XYZW and name the following.**

**(1) The pairs of opposite angles.** **Ans: **∠X and ∠Z, ∠W and ∠Y

**(2) The pairs of opposite sides.** **Ans: **Seg XW and Seg WZ, Seg WZ and Seg ZY, Seg ZY and Seg XY, Seg XY and Seg XW

**(3) The pairs of adjacent sides. **

**Ans: **Seg XW and Seg YZ, Seg WZ and Seg XY.

**(4) The pairs of adjacent angles.**

**Ans: **∠X and ∠W, ∠W and ∠Z, ∠Z and ∠Y, Y and ∠X.

**(5) The diagonals of the quadrilateral. **

**Ans: **Seg XZ and Seg WY.

**(6) The name of the quadrilateral in different ways.**

**Ans: **□XWZY, □WZYX, □ZYXW, □YXWZ.

**2. In the table below, write the number of sides the polygon has.**

**Ans: **

**3. Look for examples of polygons in your surroundings. Draw them.**

**Ans: ***Students should do this on their own.*

**4. We see polygons when we join the tips of the petals of various flowers. Draw these polygons and write down the number of sides of each polygon.**

**Ans: ***Students should do this on their own.*

**5. Draw any polygon and divide it into triangular parts as shown here. Thus work out the sum of the measures of the angles of the polygon.**

**Ans:**

Given polygon is a Pentagon which is made up of 3 triangles.

Sum of all the angles of a triangle = 180⁰

∴ Sum of all the angles of 3 triangles

= 3 × 180⁰

= 540⁰

**Ans:** Sum of all the angles of a Pentagon is 540⁰.