Trig Math/Word problem

Question

A special wedge in the shape of a regular pyramid has a square base

18.0 mm on a side. The height of the wedge is 60.0 mm. What is the total surface area of the​wedge?

Answer 1

A = l*w + l *sqrt( (w/2)^2 + h^2 ) + w * sqrt( (l/2)^2 + h^2 )

l=w=18 and h=60

A = 18*18 + 18*sqrt( 9^2 + 60^2) + 18*sqrt( 9^2 + 60^2)

= 324 + 18 * sqrt(81 + 3600) + 18 * sqrt(81 + 3600)

=445.342904969401....