Question

What does the law of cosines reduce to when dealing with a right triangle

Answer 1

Pythagorean theorem

Explanation:

We know that for a triangle if we know two sides and the included angle, the third side can be found out using cosine formula

`a^2=b^2+c^2-2bc cos A`

For a right angle triangle right angled at A this becomes

`a^2=b^2+c^2-2bc cos A\\=b^2+c^2-2bc cos 90\\=b^2+c^2-0\\=b^2+c^2`

This is nothing but Pythagorean theorem