Find the area of the lateral faces of the right triangular prism with altitude of 5 cm and base edges of length 3 cm, 4 cm, and 5 cm.

Check the picture below.

the base of it is one of the triangles, and thus, the sides are just the 3 rectangles.

notice all you have is a 3x5 rectangle, a 5x5 one and a 4x5 rectangle.

get their area, sum them up, and that's the lateral, sides, area of the triangular prism.

(3 · 5)  +  (5 · 5)  +  (4 · 5)