cosx= -1/2 i realized my ref triangle is pie /6. i know that cosine is negative in quad 2 and 3. i labeled my axis (this helped me) with pie being 6 pie over 6, pie over 2 i put 3 pie over 6, 3pie over 2 i put as 9 pie over 6, and 2 pie i made 12 pie over 6. ok since one solution is in quad 2(between 3 pie/6 and 6 pie/6) and ref angle is pie/6 i got 5pie/6 my other solution which is correct in the book is 4pie/3. so i got 4pie/3 and 5pie/6. the book says 2pie/3 and 4 pie/3. im just so frustrated, i thought i understood this stuff. its bad enough i cant understand, transformations, reflections, stretching, and compressing trig graphs, but now i cant do the equations either =( those are my particulars not my general with periods./ i then did tanx= -1 and i got 3pie/4 and 7pie/4 as my answers. or since you just need one i just got 3pie/4 + pie k/. the book says the answer is -pie over 4.