how to find 5 pi/4 theta (in radians) to sin theta

Question

jim_thompson5910 · Answer

use this unit circle http://www.regentsprep.org/Regents/math/algtrig/ATT5/600px-Unit_circle_angles_svg.jpg

anonymous · Answer

we just have to memorize those? There are no equations? What about if it ask 810 degrees?

jim_thompson5910 · Answer

yeah either that or have them on a notecard

jim_thompson5910 · Answer

810 degrees is coterminal to 810 - 360 = 450 degrees

450 degrees is coterminal to 450 - 360 = 90 degrees

so 810 degrees and 90 degrees are essentially the same angle (ie they point in the same direction)

anonymous · Answer

Thank you so much !!! 
But how do you go backwards, like tan theta negative root 3, how do you find theta in radians?

jim_thompson5910 · Answer

I recommend you memorizing something like this table (hopefully you can use this table or something like this on the test so you won't have to do as much memorizing)