What shape area requires the use of the formula "1/2 base X height" for area calculation?

The formula "1/2 base X height" is specifically used for calculating the area of a triangle. This formula is based on the geometric principle that a triangle is essentially half of a rectangle when a line is drawn from one vertex perpendicular to the base, effectively dividing it into two right triangles.

To derive the formula: the area of a rectangle is found by multiplying the base by the height. Since a triangle can be visualized as being formed from that rectangle, the area of the triangle is half of that calculated area. Hence, using 1/2 multiplied by the base and the height gives the area of the triangle accurately.

In contrast, a circle, rectangle, and square require different formulas for calculating their areas. A circle uses πr², while rectangles and squares use base times height (with squares being a specific type of rectangle where all sides are equal). Understanding the geometric properties and relationships is crucial in applying the correct formula for area calculations.