Trigonometry of Right Triangles

Here's the most important picture:

Two other trig functions are defined from these:
1. secant
2. cosecant
And there are some special triangles which are convenient to know:
1. ${\theta=\frac{\pi}{6}}$ (and ${\theta=\frac{\pi}{3}}$ )
2. ${\theta=\frac{\pi}{4}}$
Remember to make sure that your calculator is in radian mode for these calculations.
Now let's try some exercises: pp. 448, #3, 19, 31, 47, 55

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