Trigonometric Ratios
Reciprocal Trigonometric Ratios
- secant, secθ = 1/cosθ = r/x
- cosecant, cscθ = 1/sinθ = r/y
- cotangent, cotθ = 1/tanθ = x/y
Find Trigonometric Ratios Given Coordinates
Find Trigonometric Ratios Given One Ratio
Finding a Trigonometric Ratio Using a Graphing Calculator
- make sure you're in the appropriate mode (Radian/Degree)
Finding the Exact Value of a Trigonometric Ratio Example #1
- find the angle (try counting it around a circle like I do)
- remember, coterminal angles have the EXACT same trig ratio (so 3pi = pi, 5pi/2 = pi/2, 4pi = 0)
- find the reference angle (angle from x-axis)
- compare reference angle to special angle in quadrant 1 (the ratios will be the same)
- memorize the unit circle to find the exact ratio
- depending on the quadrant, find if the ratio is positive or negative (ASTC)