Solve for all $x$ given that $sin(x) + cos(2x) = 1$, where $x$ is an angle on the unit circle.
Answer 1
To solve for all $x$ given that $\sin(x) + \cos(2x) = 1$:
First, use the double-angle identity for cosine: $\cos(2x) = 2\cos^2(x) – 1$
Substitute this into the equation:
$ \sin(x) + 2\cos^2(x) – 1 = 1 $
Rearrange the equation:
$ \sin(x) + 2\cos^2(x) = 2 $
Since $\sin^2(x) + \cos^2(x) = 1$, we have $\cos^2(x) = 1 – \sin^2(x)$
So:
$ \sin(x) + 2(1 – \sin^2(x)) = 2 $
Which simplifies to:
$ \sin(x) + 2 – 2\sin^2(x) = 2 $
Thus:
$ \sin(x) – 2\sin^2(x) = 0 $
Factor out $\sin(x)$:
$ \sin(x)(1 – 2\sin(x)) = 0 $
So $\sin(x) = 0$ or $\sin(x) = \frac{1}{2}$
Therefore, the solutions are:
$ x = n\pi $
and
$ x = \frac{\pi}{6} + 2n\pi $
or
$ x = \frac{5\pi}{6} + 2n\pi $
where $n$ is any integer.
Answer 2
To solve for $x$ given that $sin(x) + cos(2x) = 1$:
Use the identity: $cos(2x) = 2cos^2(x) – 1$
Substituting:
$ sin(x) + 2cos^2(x) – 1 = 1 $
Rearranging:
$ sin(x) + 2cos^2(x) = 2 $
Using $cos^2(x) = 1 – sin^2(x)$:
$ sin(x) + 2(1 – sin^2(x)) = 2 $
Simplify:
$ sin(x) – 2sin^2(x) = 0 $
Factor:
$ sin(x)(1 – 2sin(x)) = 0 $
So $sin(x) = 0$ or $sin(x) = frac{1}{2}$
Therefore:
$ x = npi $
or
$ x = frac{pi}{6} + 2npi $
or
$ x = frac{5pi}{6} + 2npi $
where $n$ is any integer.
Answer 3
To solve for $x$ given $sin(x) + cos(2x) = 1$
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