Question

Find all the values of t in the interval [0,2pi]
cos^2(t) - sin^2(t) + sin(t) = 0

Answer 1

Convert all trigs into sine
\[\cos^2(t) - \sin^2(t) + \sin(t) = 0\]
Using \(\cos^2(t)=1-\sin^2(t)\),
\[(1-sin^2(t)) - \sin^2(t) + \sin(t) = 0\]
\[-2\sin^2(t) +\sin(t) +1=0\]
Factor it and solve for t

Answer 2

how did you get +sin in the last part?