Question 1104766
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{{{(sinx+cosx)^2 = (sinx)^2+2(sinx)(cosx)+(cosx)^2 = 1+2(sinx)(cosx) = 1+sin(2x) = 3/4}}}<br>
{{{sin(2x) = 3/4 - 1 = -1/4}}}<br>
{{{(cos(2x))^2 = 1 - (sin(2x))^2 = 1 - (-1/4)^2 = 1 - 1/16 = 15/16}}}