Question

6. The diameters of two silver discs are in the ratio 2: 3. What will be the ratio of their areas
6. If the perimeter of a semi-circular park is 72 m. find its area and radius.
7. If a wire of 440 m length is moulded in the form of a circle and a square turn-by-turn,​

Answer 1

Answer:

4:9

r=14m;area=307.72m²

Answer 2

5. The diameters of two silver discs are in the ratio 2: 3. What will be the ratio of their areas?

Sol :

Given,

Ratio of Diameter of discs = 2 : 3

let, diameters be 2x and 3x

Then, radii are

2x/2 = x

3x/2

Area of circle = πr²

Ratio of areas = πx² : π(3x/2)²

= 1 : 9/4

= 4 : 9

6. If the perimeter of a semi-circular park is 72 m. find its area and radius.

Sol :

Given,

perimeter of semi circular park = 72 m

perimeter/circumstance of a semi circle = 2πr/2 = πr

→ πr = 72

→ (22/7)r = 72

→ r = 22.9 m

Therefore,

radius of semi circular park = 22.9 m

Area of semicircle = πr²/2

= 22/7 × 22.9 × 22.9 × 1/2

= 824.07 m²