Here’s a useful guide to calculating the area of basic shapes.

RectangleArea = w × hw = width
h = height |
TriangleArea = ½b × hb = base h = vertical height |
SquareArea = a^{2}a = length of side |

TrapeziumArea = ½(a+b)×hh = vertical height |
ParallelogramArea = b × hb = base h = vertical height |
EllipseArea = πab |

SectorArea = ½r^{2}θ r = radius θ = angle in radians |
CircleArea = πr^{2} Circumference = 2πr r = radius |