Every Mechanical Engineer Should Know this Geometrical Formula

First of all  pi (π)=3.1415926535 ...

Perimeter formula 

Square	4 × side
Rectangle	2 × (length + width)
Parallelogram	2 × (side1 + side2)
Triangle	side1 + side2 + side3
Regular n-polygon	n × side
Trapezoid	height × (base1 + base2) / 2
Trapezoid	base1 + base2 + height × [csc(theta1) + csc(theta2)]
Circle	2 × pi × radius
Ellipse	4 × radius1 × E(k,pi/2) E(k,pi/2) is the Complete Elliptic Integral of the Second Kind k = (1/radius1) × sqrt(radius12 - radius22)
Area formula
Square	side2
Rectangle	length × width
Parallelogram	base × height
Triangle	base × height / 2
Regular n-polygon	(1/4) × n × side2 × cot(pi/n)
Trapezoid	height × (base1 + base2) / 2
Circle	pi × radius2
Ellipse	pi × radius1 × radius2
Cube (surface)	6 × side2
Sphere (surface)	4 × pi × radius2
Cylinder (surface of side)	perimeter of circle × height
	2 × pi × radius × height
Cylinder (whole surface)	Areas of top and bottom circles + Area of the side
	2(pi × radius2) + 2 × pi × radius × height
Cone (surface)	pi × radius × side
Torus (surface)	pi2 × (radius22 - radius12)
Volume formula
Cube	side3
Rectangular Prism	side1 × side2 × side3
Sphere	(4/3) × pi × radius3
Ellipsoid	(4/3) × pi × radius1 × radius2 × radius3
Cylinder	pi × radius2 × height
Cone	(1/3) × pi × radius2 × height
Pyramid	(1/3) × (base area) × height
Torus	(1/4) × pi2 × (r1 + r2) × (r1 - r2)2

Source: Spiegel, Murray R. Mathematical Handbook of Formulas and Tables. Schaum's Outline series in Mathematics. McGraw-Hill Book Co., 1968.