SOLUTION: how would you find the lateral area of a cone with a length of 20 cm and the radius of 9 cm. i have got 9^2 + 20^2 = 481. than take the square root of 481, which is 21.93, but i do

Algebra ->  Surface-area -> SOLUTION: how would you find the lateral area of a cone with a length of 20 cm and the radius of 9 cm. i have got 9^2 + 20^2 = 481. than take the square root of 481, which is 21.93, but i do      Log On


   



Question 446299: how would you find the lateral area of a cone with a length of 20 cm and the radius of 9 cm. i have got 9^2 + 20^2 = 481. than take the square root of 481, which is 21.93, but i don't know what to do after that?
Answer by scott8148(6628) About Me  (Show Source):
You can put this solution on YOUR website!
you found the slant height of the cone ___ this is the radius of the circle that the cone could be cut from

the LA of the cone is some fraction of the area of the circle

the fraction is the radius of the cone divided by the radius of the circle (which is the slant height of the cone)

LA = [9 / sqrt(481)] * pi * [sqrt(481)]^2