a square based pyramid

Question

with side 18cm and height 12cm, calculate the surface area.

Answer 1

Given that a square base pyramid has side(s) = 18cm and hieght(h) = 12cm

Slant hieght (l^2) = (h)^2 + (s/2)^2

                    (l^2) = (12)^2 + (18/2)^2

                    (l^2) = 144 + (9)^2

                    (l^2) = 144 + 81

                     (l^2) = 225

                      l = 15

Surface area of a square pyramid = (s)^2 + 2* s * l

                                                     = (18)^2 + 2 * 18 * 15

                                                     = 324 + 540

                                                     = 864 cm^2