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 Guiless June 28th, 2017 05:40 AM

Find the domain

f(x)=sqrtsin(cosx)

Im very confused.

 Joppy June 28th, 2017 06:26 AM

 Guiless June 28th, 2017 07:01 AM

Cosx needs to have positive value so sin(cosx) is greater or eqal to 0 ? But if cosx is for example 1/2, how can i find sin1/2 if thats not an angle but a number?

 123qwerty June 28th, 2017 07:04 AM

Quote:
 Originally Posted by Guiless (Post 573867) Cosx needs to have positive value so sin(cosx) is greater or eqal to 0 ? But if cosx is for example 1/2, how can i find sin1/2 if thats not an angle but a mumber?
Just treat the $\displaystyle \frac{1}{2}$ as if it were in radians.

 skeeter June 28th, 2017 07:41 AM

$f(x) = \sqrt{\sin(\cos{x})}$

note $-1 \le \cos{x} \le 1 \implies \sin(\cos{x}) \ge 0$ for $0 \le \cos{x} \le 1$

$0 \le \cos{x} \le 1$ for values of $x$ in quadrants I and IV

$-\dfrac{\pi}{2} + 2k\pi \le x \le \dfrac{\pi}{2} + 2k\pi$, $k \in \mathbb{Z}$

 Guiless June 28th, 2017 09:16 AM

Thank you ive got it.

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