Geometry Formulas

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

4. Sinus, Cosinus, Tangens