how to derive and memorize the trigonometric ratios of the special angles, how to use the trig ratios of the special angles to find exact values of expressions involving sine, cosine and tangent values of 0, 30, 45, 60 and 90 degrees, How to find sin, cos, tan, cot, csc, and sec of the special angles, and multiples of 90, How to remember special angles, Grade 9 math, with video lessons, examples and step-by-step solutions.