Geometry Formulas
by Vasile Stoica
1. Surfaces
1.1. cube = 6 a2
1.2. prism
1.2.1. (lateral area) = perimeter(b) L
1.2.2. (total area) = perimeter(b) L + 2b
1.2.3. sphere = 4 [pi] r2
2. Sinus, Cosinus, Tangens
3. Areas
3.1. square = a2
3.2. rectangle = ab
3.3. parallelogram = bh
3.4. trapezoid = h/2 (b1 + b2)
3.5. circle = pi r 2
3.6. ellipse = pi r1 r2
3.7. triangle = (1/2) b h
3.8. equilateral triangle = (1/4)sqrt(3) a2
3.9. triangle given SAS = (1/2) a b sin C
3.10. triangle given a,b,c = [sqrt][s(s-a)(s-b)(s-c)] when s = (a+b+c)/2 (Heron's formula)
3.11. regular polygon = (1/2) n sin(360°/n) S2
3.11.1. when n = # of sides and S = length from center to a corner