Question

If the radius of a circle is increased by 25% then its area is increased by

Answer 1

r2 = r1 + 25% × r1
r2 = r1 + 0,25r1
r2 = 1,25r1

The area of increased radius circle compared to original circle
= (π × r2²/π × r1²) × 100%
= r2²/r1² × 100%
= (1,25r1)²/r1² × 100%
= 1,5625r1²/r1² × 100%
= 156,25%

The area is increased by
= 156,25% - 100%
= 56,25%

Answer 2

Answer:

Step-by-step explanation:

r2 = r1 + 25% × r1

r2 = r1 + 0,25r1

r2 = 1,25r1

The area of increased radius circle compared to original circle

= (π × r2²/π × r1²) × 100%

= r2²/r1² × 100%

= (1,25r1)²/r1² × 100%

= 1,5625r1²/r1² × 100%

= 156,25%

The area is increased by

= 156,25% - 100%

= 56,25%