The three trigonometric ratios close trigonometric ratio A ratio written as a fraction that calculates how long one side of a right-angled triangle is compared to another, based on a given angle, Ɵ.

Angle Formulas in Trigonometry: Definition, ... where θ is the angle in a right-angled triangle. Multiple Angle Formulas: Multiple angles are of the form sinnθ, cosnθ, and tannθ.

A 3,700-year old Babylonian clay tablet reveals an ancient method of constructing right-angled triangles that makes it the world’s oldest and most accurate trigonometric table.