### Home > INT3 > Chapter 9 > Lesson 9.2.1 > Problem9-102

9-102.

Should $y = \text{sin}\left(x\right)$ and $y = \text{cos}\left(x\right)$ both be parent functions, or is one the parent of the other? Give reasons for your decision.

Notice that the sine curve could be shifted horizontally to match the cosine curve, or vice-versa.
What is the horizontal shift?

$\text{Since } y = \text{cos }x \text{ is the same as }y = \text{sin }\left(x+\frac{\pi}{2}\right),\text{ only one of these needs to be the parent graph.}$