Geometry Formulas
by Vasile Stoica

1. Areas
1.1. square = a2
1.2. rectangle = ab
1.3. parallelogram = bh
1.4. trapezoid = h/2 (b1 + b2)
1.5. circle = pi r 2
1.6. ellipse = pi r1 r2
1.7. triangle = (1/2) b h
1.8. equilateral triangle = (1/4)sqrt(3) a2
1.9. triangle given SAS = (1/2) a b sin C
1.10. triangle given a,b,c = [sqrt][s(s-a)(s-b)(s-c)] when s = (a+b+c)/2 (Heron's formula)
1.11. regular polygon = (1/2) n sin(360°/n) S2
1.11.1. when n = # of sides and S = length from center to a corner
2. Volumes
2.1. cube = a3
2.2. rectangular prism = a b c
2.3. irregular prism = b h
2.4. cylinder = b h = [pi] r2 h
2.5. pyramid = (1/3) b h
2.6. cone = (1/3) b h = 1/3 [pi] r2 h
2.7. sphere = (4/3) [pi] r3
2.8. ellipsoid = (4/3) pi r1 r2 r3
3. Surfaces
3.1. cube = 6 a2
3.2. prism
3.2.1. (lateral area) = perimeter(b) L
3.2.2. (total area) = perimeter(b) L + 2b
3.2.3. sphere = 4 [pi] r2