Question 1115504
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<pre>
7 sin^2 x - 14 sin x + 2 = -5  ====>


7*sin^2(x) - 14*sin(x) + 7 = 0  ====>


sin^2(x) - 2*sin(x) + 1 = 0  ====>


{{{(sin(x)-1)^2}}} = 0  <====>


sin(x) = 1  <====>  x = {{{pi/2+2*k*pi}}},  k = any integer 0, +/-1, +/-2, . . . 
</pre>

Solved.