The values of sine, cosine, tangent, and cotangent can be found using the trigonometric unit circle, which is an excellent source of information about the trigonometric functions. Graphs and properties of trig functions. Inverse trig functions. Trig Functions of Special Angles. sine 0, sine 30, sine 60, sine 90, cosine 0, cosine 30, cosine 60
The Pythagorean Identity. The relationship between right triangles and trigonometric functions of angles on the unit circle can also be used to derive a new identity. Consider the same right triangle we used above. By using the Pythagorean Theorem and the definitions of cosine and sine, we can establish a new identity.