Question 1136549
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<pre>
(a)  sin(x) = {{{1/2}}}.    The solutions are  x = {{{pi/6}}} in QI  and  x = {{{5pi/6}}}  in QII.



(b)  cos(x) = {{{-1/2}}}.   The solutions are  x = {{{2pi/3}}} in QII  and  x = {{{4pi/3}}}  in QIII.



(a)  sin(x) = {{{-1/2}}}.    The solutions are  x = {{{7pi/6}}} in QIII  and  x = {{{11pi/6}}}  in QIV.
</pre>

Answered and solved.



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To make the formulation precisely correct from the point of view of English grammar, take off the very first line from the post.