Sum of the interior angles of a polygon. (number of sides - 2) 180.
Area of a rectangle or a parallelogram. A = bh.
Area of a triangle. A = ½ bh.
Area of a trapezoid. A = ½ (b₁+b₂) h.
Area of a circle. A = πr²
Circumference of a circle. C = πd.
Surface area of a prism. S = 2B + Ph.
Surface area of a cylinder.