6.2 Trigonometric Ratios
The functions that relate angles to side in a right-angled triangle are known as trigonometric functions (sine, cosine, tangent etc.) Their development is rooted in ancient geometry, blossomed through Indian and Islamic mathematics and became formalized in Europe during the Renaissance. Today, these functions are indispensable tools in both theoretical and applied sciences. Trigonometry has since been extensively used in various scientific disciplines such as physics (especially wave theory) engineering, and computer graphics.