Question

whats the lateral area of a right circular cone if the diameter of the base is 4m and the slant height of the cone is 15m? round your anwser the the nearest whole number.

Answer 1

First is to understand the terms. Lateral area is the surface area of a 3D figure, excluding the area of any base. 
Laterial Area (L.A.) of a right cone = pi*radius*slant height 
radius = 1/2 * diameter 
L.A. = pi*(1/2)*(4)*(15)=30*pi 

the formula for this is pi*r*rt(r^2 + h^2). If the diameter is 4, then the radius is 2. If the slant height is 15, then to get the real height we use the Pythagorean Theorem and get rt(221). So the lateral area is pi*2*rt(2^2 + (rt221)^2)...= 2pi*rt(225) = 30pi = 94.248 meters squared which is rounded to 94 meters squared.