Area Calculator

Area = π × r², where r is the radius (half the diameter). For a circle with diameter 10, radius = 5, area = π × 25 ≈ 78.54 square units. If you know the circumference C, area = C²/(4π).

Heron's formula finds a triangle's area from its three sides: Area = √(s(s-a)(s-b)(s-c)), where s = (a+b+c)/2 is the semi-perimeter. It works for any triangle without needing the height.

Break it into simpler shapes (rectangles, triangles, circles). Calculate each area separately, then add them together. This technique, called decomposition, works for any polygon or compound shape.