What is the approximate surface area of a cone with a slant height of 4cm and a radius of 3cm?

The surcace area is given by

pi * r ( r + L)      where r is the radius and L  is the slant height  .... so we have

pi* 3(3 + 4)   =   pi* 3(7)  =  21 pi   = 65.97 sq cm