Notes
cosine rule

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Cosine Rule

The cosine rule extends Pythagoras' Theorem to all triangles.

CosineRule.png

With side lengths and angles as in the above diagram then:

c 2=a 2+b 2−2abcos(C) c^2 = a^2 + b^2 - 2 a b \cos(C)

(and the same with other permutations of the letters)

Created on June 24, 2021 10:38:22 by Andrew Stacey
Views: Print | TeX | Source | Linked from: Pythagoras, five semi-circles solution, parallelogram law, three triangles in a circle in a triangle solution, three triangles in a circle in a triangle techniques, stacked triangles solution, stacked triangles techniques