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>>46832
your approach on the right side is correct, you just need to keep x = 0.5 sin^-1(sqrt(3)/2) because cos^2(x) is asked and use another variable, say a.

a = sin^-1(sqrt(3)/2)
sin a = sqrt(3)/2 => cos a = 1/2

Now use the identity:

cos^2(x) = 1/2 + cos(2x)/2 = 1/2 + cos (a)/2 = 1/2 + 1/4 = 3/4
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let a = arcsin(sqrt(3)/2) you shouldn't compute the value of a, you should use the formula instead

then it is (cos(a/2))^2 = 1/2 + (1/2)*cos(2*(a/2))
=1/2 + cos(a)/2
=1/2 + sqrt(1-sin^2(a))/2
=1/2 + sqrt(1-3/4)/2 = 1/2 + (1/2)/2
=1/2 + 1/4 = 3/4

but it is not the right way
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>>46832
Eassy as fuck.
You should go to /sci/
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>>46995
thank you!