I've been given a couple of assignments from my teacher, everything I answered correctly except this one task.

A=216Picm^2

s= 15cm

------>This how far I've gone

A=r^2Pi+rxPixs

216=r^2+rxs

I've figured out how to extract "r" but I can't seem to extract it with 2 uknowns.

Cone is composed of 2 right-angled triangles. So I used one of the triangles to extract the "r" using Pythagoras theorem.

And I got this: s^2=r^2+s^2h

What do I do next?