Well 85% of 25 is 21.25. So the closest ones would be 20 or 22. Well let's check out the difference's. 21.25-20= 1.25.....22-21.25=.75. well clearly .75 is smaller than 1.25 so your answer would be 22. 85% of 25 is closest to 22.
I believe it's<span> 8cos(x)⁸ - 16cos(x)⁶ + 10cos(x)⁴ - 2cos(x)².
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Alternately, you can write [</span><span><span>1 / (tan(2x) - cot(2x))] + [cos(8x) / (tan(2x) - cot(2x))].
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