(cos x - siny)/ (cosy - sinx) = (cosy + sinx)/(cosx+siny)

- Thanks for the help

2. Write sines in terms of cosines, meaning if you have sin x write cos(pi/2 - x).
Then use the sine and cosine sum/difference formulas.

3. Originally Posted by ThePerfectHacker
Write sines in terms of cosines, meaning if you have sin x write cos(pi/2 - x).
Then use the sine and cosine sum/difference formulas.

this might be a stupid question, but if you use the sum/difference formula on
cos (2/pi-x) wont you just be back at sin x?