Area of a parallelogram = base × height.
Area of rhombus = ½ product of the diagonals.
Area of a triangle = ½ base × perpendicular height.
Area of equilateral triangle = square of side × 0·433.
Area of trapezium = ½ sum of two parallel sides × height.
Area of any right-lined figure of four or more unequal sides is found
by dividing it into triangles, finding area of each and adding
together.
Area of regular polygon = (1) length of one side × number of sides ×
radius of inscribed circle; or (2) the sum of the triangular areas
into which the figures may be divided.
Circumference of a circle = diameter × 3·1416.
Circumference of circle circumscribing a square = side × 4·443.
Circumference of circle = side of equal square × 3·545.
Length of arc of circle = radius × degrees in arc × 0·01745.
Area of a circle = square of diameter × 0·7854.
Area of sector of a circle = length of arc × ½ radius.
Area of segment of a circle = area of sector − area of triangle.
Side of square of area equal to a circle = diameter × 0·8862.
Diameter of circle equal in area to square = side of square × 1·1284.
Side of square inscribed in circle = diameter of circle × 0·707.
Diameter of circle circumscribing a square = side of square × 1·414.
Area of square = area of inscribed circle × 1·2732.
Area of circle circumscribing square = square of side × 1·5708.
Area of square = area of circumscribing circle × 0·6366.
Area of a parabola = base x ⅔ height.
Area of an ellipse = major axis × minor axis × 0·7854.
Surface of prism or cylinder = (area of two ends) + (length ×
perimeter).
Volume of prism or cylinder = area of base × height.
Surface of pyramid or cone = ½(slant height × perimeter of base) +
area of base.
Volume of pyramid or cone = (⅓)(area of base × perpendicular height).
Surface of sphere = square of diameter × 3·1416.
Volume of sphere = cube of diameter × 0·5236.
Volume of hexagonal prism = square of side × 2·598 × height.
Volume of paraboloid = ½ volume of circumscribing cylinder.
Volume of ring (circular section) = mean diameter of ring × 2·47 ×
square of diameter of section.