Learn the formulas and graphs of sin, cos and tan, the three basic trigonometric functions, with examples and videos. Find out how to use the sine, cosine and tangent rules and the Pythagoras identity to solve problems involving right-angled triangles. We know that sin, cos, and tan are the reciprocals of cosec (or csc), sec, and cot functions. Thus, we can derive 3 more formulas related to sin, cos, and tan. sin A = 1/csc A (or) csc A = 1/ sin A. cos A = 1/sec A (or) sec A = 1/cos A. tan A = 1/cot A (or) cot A = 1/tan A. While sine and cosine are readily identifiable as the projections of the radius on the vertical and horizontal axis, we need to see the definition of the tangent to understand how to find it and visualize it: \tan (\alpha) = \frac {\sin (\alpha)} {\cos (\alpha)} tan(α) = cos(α)sin(α) .

sin cos tan rules