Which formula would you use to calculate the area of a triangle?

To calculate the area of a triangle, the correct formula is the one that involves multiplying the base (b) by the height (h) and then taking half of that product. This is expressed as A = 1/2 * b * h.

The rationale behind this formula is rooted in the geometric properties of triangles. A triangle can be thought of as half of a rectangle when divided diagonally from one corner to the opposite side. Therefore, if you take the area of the rectangle (which is base times height) and divide it by two, you arrive at the formula for the area of a triangle.

The other options do not appropriately represent the area of a triangle. The formula for a rectangle (base times height) would result in a larger area than what is geometrically accurate for a triangle. The option that adds twice the base and twice the height doesn't have any relevance for area calculation, while the formula involving πr² is specifically meant for the area of a circle, which is unrelated to triangles.

Thus, the formula A = 1/2 * b * h accurately reflects the needed relationship for determining the area of a triangle.