Answer to Question #6946 in Trigonometry for Akhtar Rasool

Question

Dear Expert mathematicain,
what is the fundamentaal law of trigonometry?

best wishes,

Akhtar Rasool.

Answer 1

By "fundamental theorem of trigonometry" is often meant sin²(x) + cos²(x) = 1, it is actually the Pythagorean Theorem. if you have a right
triangle with a hypotenuse of one, sin(x) is one leg, and cos(x) is the
other. The Pythagorean Theorem states that a² + b² = c² and therefore sin²(x) + cos²(x) = 1.