Multiply circumference by one-quarter of the diameter.
Or multiply the square of diameter by 0.7854.
Or multiply the square of circumference by .07958.
Or multiply the square of ¹⁄₂ diameter by 3.1416.
Contents of cylinder = area of end × length. Contents of wedge = area
of base × ¹⁄₂ altitude. Surface of cylinder = area of both ends ×
length × circumference. Surface of sphere = diameter squared × 3.1416,
or = diameter × circumference. Contents of sphere = diameter cubed ×
.5236. Contents of pyramid or cone, right or oblique, regular or
irregular = area of base × ¹⁄₃ altitude. Area of triangle = base × ¹⁄₂
altitude. Area of parallelogram = base × altitude. Area of trapezoid =
altitude × ¹⁄₂ the sum of parallel sides.