What is the area of the triangle whose sides are 5, 9, and 13?

The triangle with sides 5, 9, and 13 is a Pythagorean triangle, which means it's a right triangle. The area of a right triangle can be found using the formula 1/2 * base * height. Here, we can take 5 and 9 as the base and height (it doesn't matter which one is the base and which one is the height).

Step 1: Multiply the base and height. 5 * 9 = 45

Step 2: Divide the result by 2. 45 / 2 = 22.5

So, the area of the triangle is 22.5 square units.