Identify the shape
Choose the correct area formula for that shape
Substitute the given measurements into the formula
Use consistent units (convert if needed)
Calculate the area
Report the result with square units (e.g., cm², m²)
Rectangle: (A = l times w)
Square: (A = s^2)
Triangle: (A = frac{1}{2} times b times h)
Parallelogram: (A = b times h)
Trapezoid: (A = frac{(b_1 + b_2)}{2} times h)
Circle: (A = pi r^2)
Ring (annulus): (A = pi(R^2 – r^2))
Rhombus: (A = frac{d_1 times d_2}{2})
Ellipse: (A = pi a b)
Regular polygon: (A = frac{1}{2} times P times a) (perimeter (P), apothem (a))
Composite figures: split into known shapes, find each area, add/subtract as needed
Irregular shapes on a grid: count full squares, estimate partial squares, add totals
Coordinate/planar polygon (shoelace formula): (A = frac{1}{2}left|sum (x_i y_{i+1} – y_i x_{i+1})right|)