Question

A varies inversely with the square of r and when r = 4, A = 75. Find r when A = 48

r=​

Answer 1

Answer:

r = 3.2

Step-by-step explanation:

If A varies inversely with the square of r, then A = kr^2

75 = k*4^2 = 16k

k = 75/16

Now A = (75/16)*r^2

48 = (75/16)*r^2

r^2 = 48(16/75) = 256/25

r = $\sqrt{\frac{256}{25} }$ = 16/5 = 3.2