Question 1137220: 3-5cosx+5sin^2x=0 solve for x
Answer by greenestamps(13203)   (Show Source):
You can put this solution on YOUR website!
The general technique for solving an equation involving cos(x) and sin^2(x) is to replace sin^2(x) with 1-cos^2(x) to obtain a "quadratic" equation with cos(x) as the "variable"; then try to solve by factoring.
Similarly, if an equation involves sin(x) and cos^2(x), you would get a quadratic in sin(x) by replacing cos^2(x) with 1-sin^2(x).
Unfortunately, in this example the resulting quadratic in cos(x) does NOT factor, making it necessary to solve using a calculator.
Then, since you have to use a calculator to solve the problem after converting the original equation into a quadratic in cos(x), you might as well just solve the original equation using a calculator.
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