Laws

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

Law of sines
Law of cosines « Correct result
Law of tangents
Law of cotangents

Step-by-step explanation:

$$\begin{gathered} c^2=a^2+b^2-2ab\cos \gamma \\ \gamma =90^{\circ }\Rightarrow \cos 90^{\circ }=0 \\ {c}^2=a^2+b^2-2ab\cos 90^{\circ } \\ {c}^2=a^2+b^2-2ab\cdot 0 \\ {c}^2=a^2+b^2 \end{gathered}$$

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