haven't taken math in a while and I'm taking a trigonometry class. I believe i learned this in algebra but i can't remember how its done.
cos = +/-√1-225/289
(basically i don't understand how to do the square root part of this. its the square root of 1- 225 over 289.
The answer for this is = +/- 8/17
**no clue how they got 8/17.
thx and godbless if anybody can help me