Question 908554
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Use the zero product rule, i.e. *[tex \Large ab\ =\ 0\ \Leftrightarrow\ a\ =\ 0\ \small\vee\Large\ b\ =\ 0]


So the roots of your equation are all angles in the given interval where *[tex \Large \sin x\ =\ 0] or *[tex \Large \cos x\ =\ 0].  Refer to any available copy of the unit circle. 


John
*[tex \LARGE e^{i\pi}\ +\ 1\ =\ 0]
My calculator said it, I believe it, that settles it
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