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Question

$sin2x-2cosx+0.25=0$

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Answer 1 · 2018-01-24T12:10:22

$sin(2x)=2sinx cosx$ then

$sin2x-2cosx+0.25=2sinx cosx-2cosx+1/4=0$

then

$cos x = 1/(8(sinx-1))$ but

$sin^2x+cos^2x = 1$ so

$sin^2x+1/(64(sinx-1)^2)=1$ and now solving for $sin x$ we have the real solutions as

$sinx = {(-0.998041),(0.794264):}$

The next steps are left to the reader.