The triangle formed from the height of the cone and the radius of its base is a special 3,4,5 triangle. The slant height is 5cm.
Recall that the area of a circle = pi*r^2
Substitute 3 in for r
Area = pi * (3)^2 = 9pi
SA = pi*r*l + B
Substitute our values into the equation
SA = pi * 3 * 5 + 9pi
SA = 15pi + 9pi
SA = 24pi cm^2
