## Unit circle and trig. functions – About -pg. 1/7

Posted in Math Theory by Lia on 05/23/2017

## 1.  About unit circle and trig. functions.

### As showninRight triangle and trigonometric functions:

$\fn_cm&space;\sin&space;\alpha=\frac{\textbf{opposite}\;&space;\textbf{leg}}{\textbf{hypotenuse}}\;&space;\;\textbf{and}\;&space;\;\cos\alpha=\frac{\textbf{adjacent}\;&space;\textbf{leg}}{\textbf{hypotenuse}}$

### Knowing the values and signs of sine and cosine  for an angle and  using the relationship between different trigonometric functions ( see Right triangle and trigonometric functions ) we can find out the values and signs for the other trigonometric functions (tangent, cotangent, secant and cosecant).

$\fn_cm&space;\tan&space;\alpha=\frac{\sin&space;\alpha&space;}{\cos&space;\alpha&space;};\;&space;\cot&space;\alpha=\frac{\cos&space;\alpha&space;}{\sin&space;\alpha&space;};\;&space;\sec&space;\alpha=\frac{1}{\cos&space;\alpha&space;};\:\csc&space;\alpha=\frac{1}{\sin&space;\alpha&space;}$

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