Euclid wrote down a version of it, despite lacking trigonometry, providing separate cases for obtuse and acute triangles.
Euclid wrote down a version of it, despite lacking trigonometry, providing separate cases for obtuse and acute triangles. Independently rediscovered and proven by François Viète in the 16th century, it is a generalization of the Pythagorean Theorem and can be proven using it. For ten points, identify this triangle law, associating the square of a side of any triangle with the sum of the squares of the other two sides and the angle between them.
Euclid wrote down a version of it, despite lacking trigonometry, providing separate cases for obtuse and acute triangles.
{law of cosines}