My Math Forum

My Math Forum (http://mymathforum.com/math-forums.php)
-   Trigonometry (http://mymathforum.com/trigonometry/)
-   -   Find the domain (http://mymathforum.com/trigonometry/341027-find-domain.html)

Guiless June 28th, 2017 04:40 AM

Find the domain
 
f(x)=sqrtsin(cosx)

Im very confused.

Joppy June 28th, 2017 05:26 AM

Maybe elaborate on your confusion.

Guiless June 28th, 2017 06:01 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 06:04 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 06:41 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 08:16 AM

Thank you ive got it.


All times are GMT -8. The time now is 12:05 PM.

Copyright © 2018 My Math Forum. All rights reserved.