What is the formula for the area of a triangle?

• A. Base x height
• B. (Base x height)/2
• C. (Base + height)/2
• D. pi x r^2

Answer: (B)

When finding the area of a triangle, you use the base and the height. Multiply the base by the height, then divide by two. The height is the perpendicular distance from the base to the opposite vertex, and the base can be any side you choose to treat as the base. This works because a rectangle with the same base and height has area base×height, and a triangle with that same base and height occupies exactly half of that rectangle, so its area is half of base×height. Therefore the correct formula is base×height divided by two. The other options describe the area of a rectangle (base×height), a nonstandard average formula, and the area of a circle (πr²).