algebraic proportionality help please?

Question

i need to find a general formula to describe the variation and the constant of proportionality.
....A is directly proportional to both h and the square of the radius, r. A=100(pi) when r=5 and h=2. PLEASE HELP. thnak you!!!!!!

Answer 1

A = L*h ...........l is constant
and A= Mr*r ...............M is a constant

so A = k*h*r*r
this is the required relation

100(pi) = 25*2*k
gives k = 2(pi)

Answer 2

If A is directly proportional to h and r^2,
then it is directly proportional to their product, hr^2.
This is written as : A = khr^2, where k is a constant.

Now we have an equation where
we can plug in the given values.

100π = k * 2 * 5^2 = 50k
Therefore, k = 100π / 50 = 2π

The general equation is thus :
A = 2πhr^2