Posted by **anonymous** on Tuesday, October 26, 2010 at 11:13pm.

Does 'using the unit circle' just mean that I use these:

In Quadrant I, theta=beta

In Quadrant II, theta=180-beta

In Quadrant III, theta=180+beta

In Quadrant IV, theta=360-beta

Because the whole lesson we did was about that sort of thing, which is all review from last year, but then at the end we did a quick example saying something about unit circles and every question in my homework is 'using the unit circle'.

- Math -
**Henry**, Wednesday, October 27, 2010 at 7:26pm
The unit circle is the graph of x^2 + y^2 = 1. The radius vector is viewed as the hyp. of a rt triangle and has a magnitude of 1. A vector is assumed to

rotate CCW. So if we start at 0 deg and

calculate the coordinates of the point

where the vector intersects the circle,

we get:

x = 1*cos0 = 1,

y = 1*sin0 = 0,

p(x , y) = (1 , 0).

So coordinates give us the sine and

cosine at any point on the circle.

For a complete graph and more detailed

INFO, GOOGLE,MATH:Unit circle.

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