Area of a triangle

base * 1/2 altitude.

Area of a parallelogram

multiply base by altitude.

Area of a trapezoid

altitude * 1/2 the sum of parallel sides.

Area of a trapezium

divide into two triangles and find area of the triangles.

Circumference of circle

diameter * 3.1416.

Diameter of circle

cicumference * .3183.

Area of circle

square of the diameter multiplied by .7854.

Area of circular ring

diameters of the two circles * difference of diameter and that product by .7854.

Side of square that shall equal area of circle

diameter * . 8812 or circumference * .2821.

Diameter of circle that shall contain area of a given square

side of square * 1.1284.

Surface of cylinder or prism

area of both ends + length * circumference.

Contents of cylinder or prism

area of end X length.

Surface of sphere

diameter * circumference.

Contents of sphere

diameter3 * .5236.

Contents of pyramid or cone

area of base * 1/3 altitude.

Surface of frustum of cone or pyramid

sum of circumference at both ends * slant height + area of both ends.

Contents of frustrum of cone= or pyramid

multiply areas of two ends together and extract square root. Add to this root the two areas and * 1/3 altitude.

Contents of a wedge

area of base * 1/2 altitude.