Question

Find the surface area of a square pyramid with side length 5 cm and slant height 6 cm.

Answer 1

Don't you have just 4 identical triangles ?

Each triangle has area of (1/2)(base)(height)
= (1/2)(5)(6) = 15 cm^2

so you have 4 of those .....

You didn't say if the area of the base is included.
If so, just add 25 cm^2 to the sum of the 4 triangles