Hello!
First you have to find the third side of the triangle using the Pythagorean Theorem

Square the numbers

Add

Take the square root of both numbers

Now we know all the numbers we need
To find the lateral area of a triangular prism you use the equation
Al = (a + b + c)h
Al is lateral area
a, b, c are the side lengths of the triangle
h is height
Put in the values we know

Combine like terms

Simplify the square root

Al = about 137.689
The answer is

or 137.689
Hope this helps!