## kaylalynn Which of the following functions is not a sinusoid? y = sin x y= Sqrtx y = cos x None of the above are sinusoids. 9 months ago 9 months ago

1. ghazi

definitely $\sqrt x$ is not a sinusoid , it doesn't vary as a sine wave or a cosine wave

2. kaylalynn

thats what i was thinkging thanks!!

3. ghazi

|dw:1369863782806:dw|

4. kaylalynn

btw does a sinusoid have to go below the x axis??

5. ghazi

no, sinusoid wave are those which show a smooth repetitive variation or oscillation , like a sine wave or a cosine wave , it doesn't have to go below x axis, if you shift the origin up with respect to the original origin you wont have it below x axis, its just a general trend

6. ghazi

|dw:1369863941221:dw| O new is the new origin

7. reemii

I would say yes (it has to go below), since I take as definition that a sinusoid is a function of the form $$\lambda \sin(\alpha x + \phi)$$, with $$\lambda, \alpha, \phi\in\mathbb R$$. But you allow a vertical translation in your definition the answer is yes..

8. kaylalynn

how bout this then??

9. reemii

you have to find in your definition in your course. (wikipedia says that the general form allows for a vertical shift). If your definition is the general definition, then there are two sinusoid curves on this picture.