Posted by **Liddy** on Friday, June 10, 2011 at 4:38pm.

1.)P(-15/17,-8/17) is found on the unit crcle. find sin0 and cos0.

2.)solve: x=Arc tan(-sq root3).

3.)find sec0 if sin0=-4/5 and 270 degrees<0<360 degrees.

- Algebra II -
**Reiny**, Friday, June 10, 2011 at 11:14pm
1. Any point P on the unit circle has coordinates (cosØ, sinØ)

so cosØ = -15/17

sinØ = -8/17

2. x = arctan(-√3)

or

tanx = -√3/1 , we know tan 60°=+√3

x must be in II or IV

x = 120° or 300° or -60° or ....

3. sinØ = -4/5

Ø is in IV

recognize the 3 4 5 triangle

so cosØ = 3/5

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