Circle: C = Î d, in which Î is 3.1416 and d the diameter.
Triangle: A = (ab)/2 , in which a is the base and b the height.
Square: A = a2, in which a is one of the sides.
Rectangle: A = ab, in which a is the base and b the height.
Trapezoid: A = (h(a + b))/2, in which h is the height, a the longer parallel side, and b the shorter.
Regular pentagon: A = 1.720a2, in which a is one of the sides.
Regular hexagon: A = 2.598a2, in which a is one of the sides.
Regular octagon: A = 4.828a2, in which a is one of the sides.
Circle: A = Î r2, in which Î is 3.1416 and r the radius.
Cube: V = a3, in which a is one of the edges.
Rectangular prism: V = abc, in which a is the length, b is the width, and c the depth.
Pyramid: V = (Ah)/3, in which A is the area of the base and h the height.
Cylinder: V = Î r2h, in which Î is 3.1416, r the radius of the base, and h the height.
Cone: V = (Î r2h)/3, in which Î is 3.1416, r theradius of the base, and h the height.
Sphere: V = (Î 4r3)/3, in which Î is 3.1416 and r the radius.
Degrees Fahrenheit to Degrees Celsius: TC = 5/9 (TF, 32)
Degrees Celsius to Degrees Fahrenheit: TF = 9/5 TC + 32
Degrees Celsius to Kelvin: TK = TC + 273.15
Distance in feet traveled by falling body: d = 16t2, in which t is the time in seconds.
Speed of sound in feet per second through any given temperature of air: take the square root of (273 + t), in which t is the temperature Centigrade, multiply it by 1087, and divide the result by 16.52.
Cost in cents of operation of electrical device: C = (Wtc)/1000, in which W is the number of watts,t the time in hours, and c the cost in cents per kilowatt-hour.
Conversion of matter into energy (Einstein’s Theorem): E = mc2, in which E is the energy in ergs, m the mass of the matter in grams, and c the speed of light in centimeters per second: (c2 = 9 Ã— 1020)
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