Area Calculator — rectangles, triangles, trapezoids

Formula

A_{\text{triangle}} = \tfrac{1}{2} b h

A triangle is half of a parallelogram with the same base and height.

A_{\text{trapezoid}} = \tfrac{1}{2}(a + b) h

Average the two parallel sides, then multiply by the height.

A = ½ × 10 × 6 = 30 square units.

Square units of whatever you entered — e.g. cm in gives cm².

Use the Circle Calculator, which also gives exact answers in terms of π.