Question

If the if the ratio of diameter of two circles is 4 ratio 5 then find the ratio of areas of both circles

Answer 1

$\frac{d1}{d2} = \frac{4}{5} \\ \frac{a1}{a2} = \frac{\pi {(r1)}^{2} }{\pi {(r2)}^{2} } = {( \frac{4}{5}) }^{2} = \frac{16}{25}$

Answer 2

Heya,

According to the question,

Ratio of diameter of two circles = 4:5

So,
Let diameter of 1st circle be = 4x
then, radius of 1st circle = 4x/2 = 2x

And let diameter of 2nd circle be = 5x
then, radius of 2nd circle = 5x/2

Area of 1st circle = πr²
= π(2x)²
= 4x²π

Area of 2nd circle = πr²
= π(5x/2)²
= 25/4x²π

Ratio of area of two circles = 4x²π/(25/4x²π)
= 4/(25/4)
= 16/25
= 16:25

So, ratio of area of two circles will be = 16:25

Hope this helps....:)