Write the formula that estimates the change that occurs in the total surface area of...

Question

A right circular cone when the radius changes from r to r+dr and height remains unchanged. The equation is S=pir²+pirsqrt(r²+h²). I got dS=2pirdr+1/2pir(r²+h²)^-1/2(2rdr+2h), not sure where I go from here though--any help or guidance would be greatly appreciated.

Answer 1

Hi Molly

dS=2pirdr+1/2pir(r²+h²)^-1/2(2rdr+2h), is almost the correct answer, the 2h should not be there because h is a constant so dh/dr=0

Hope this helps

Jim