Which of the following formulas would find the lateral area of a right cone where r is the radius and s is slant height?

a. la=1/2

b. la=2 pi rs
c. la=pi rs
d. la=rs

For a right circular cone, the lateral surface area is given by,

The value of square root of h²+r² is equal to slant height s.

So replacing the value of square root of (h²+r²) by s in the formula for lateral surface area , we have

L.S.A. = pi * r * s

where s is slant height of the given right cone.

The lateral surface area of a right cone is pi*r*s.

Option C is the correct answer.