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 June 28th, 2017, 04:40 AM #1 Newbie   Joined: Jun 2017 From: Serbia Posts: 3 Thanks: 0 Find the domain f(x)=sqrtsin(cosx) Im very confused.
 June 28th, 2017, 05:26 AM #2 Senior Member   Joined: Feb 2016 From: Australia Posts: 1,843 Thanks: 657 Math Focus: Yet to find out. Maybe elaborate on your confusion. Thanks from 123qwerty
 June 28th, 2017, 06:01 AM #3 Newbie   Joined: Jun 2017 From: Serbia Posts: 3 Thanks: 0 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? Last edited by Guiless; June 28th, 2017 at 06:04 AM.
June 28th, 2017, 06:04 AM   #4
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Quote:
 Originally Posted by Guiless 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.

 June 28th, 2017, 06:41 AM #5 Math Team     Joined: Jul 2011 From: Texas Posts: 3,044 Thanks: 1627 $f(x) = \sqrt{\sin(\cos{x})}$ 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 $-\dfrac{\pi}{2} + 2k\pi \le x \le \dfrac{\pi}{2} + 2k\pi$, $k \in \mathbb{Z}$
 June 28th, 2017, 08:16 AM #6 Newbie   Joined: Jun 2017 From: Serbia Posts: 3 Thanks: 0 Thank you ive got it.

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