Area of Quadrilaterals and Polygons

Quadrilaterals

Square

P = 4 s A = s^{2} = \frac{1}{2} d^{2}

d = s√2 the diagonal

Rectangle

P = 2 (l + w) A = l w d = \sqrt{l^{2} + w^{2}}

Parallelogram

A = b h

Rhombus or kite

A = \frac{1}{2} d_{1} d_{2}

Trapezoid

A = \frac{1}{2} (b_{1} + b_{2}) h = m h

midsegment m = (b₁ + b₂)/2

Area from the apothem

A = \frac{1}{2} a P

a apothem, P perimeter

Trouble with a formula often traces back to an earlier skill. Our free check-in finds the exact gap. A tutor then works on it with your child.