# Laws

From which law follows directly the validity of Pythagoras' theorem in the right triangle?

« Correct result

#### Solution:

$c^2 = a^2 + b^2 - 2ab \cos \gamma \ \\ \ \\ \gamma = 90^\circ \Rightarrow \cos 90^\circ =0 \ \\ c^2 = a^2 + b^2 - 2ab \cos 90^\circ \ \\ c^2 = a^2 + b^2$

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#### Following knowledge from mathematics are needed to solve this word math problem:

Cosine rule uses trigonometric SAS triangle calculator. See also our trigonometric triangle calculator. Pythagorean theorem is the base for the right triangle calculator.

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