David
Using Pythagoras its height is 15 mm and by adding its 5 surfaces areas together it works out as 680 square mm
Mercy
The Formula for the surface area of a right triangular prism is calculated by adding up the area of all rectangular and triangular faces of a prism. The surface area of a right triangular prism formula is bh+(s1 + s2 + h)L. Where 'b' is the bottom edge of the base triangle.