Question

Q4. Find the area of the shaded region. All the measurements are in cm.
16,4,10
​

Answer 1

Answer:

(i) Outer length = 20 cm

breadth = 16 cm

Outer area = l x b

= 20 x 16 = 320 cm^2

2

Inner Length = 15 cm

Inner Breadth = 10 cm

Inner area = 15 x 10 = 150 cm^2

2

Area of shaded region = Area of whole region - Area of unshaded region

= 320 - 150 = 170 cm^2

2

(ii) Outer Length = 30 cm

Outer Breadth = 20 cm

Outer area = l x b

= 30 x 20 = 600 cm^2

2

Inner Length = 12 cm and Inner Breadth = 12 cm

Inner area = l x b = 12 x 12 = 144 cm^2

2

Area of shaded region = Area of outer region - Area of inner region

= 600 - 144 = 456 cm^2

2

(iii) Area of shaded region = Area of outer region - Area of unshaded region

= 40 x 40 - 32 x 15

= 1600 - 480 = 1120 cm^2

2

(iv) Area of shaded region = Area of outer region - Area of inner region

= 40 x 40 - 15 x 15

= 1600 - 225 = 1375 cm^2

2

(v) Area of shaded portion

= 2 x 20 + 2 x 8 + 2 x (12 + 2)

= 40 + 16 + 28 = 84 cm^2