Question

Let $\theta$ be an angle in standard position with (x, y) a point on the terminal side of $\theta$ and r = $\sqrt{x^2+y^2}\ne 0$. What is cos $\theta$?

• A. $\frac{y}{r}$
• B. $\frac{r}{y}$
• C. $\frac{x}{r}$
• D. $\frac{r}{h}$

Answer 1

The correct option is C $\frac{x}{r}$

By using Pythagoras theorem, we will find the value of hypotenuse.
$x^2+y^2=r^2$
So, $\cos \theta$ = $\frac{adjacentside}{hypotenuse}$ = $\frac{y}{r}$

$\cos \theta$ = $\frac{x}{r}$

So, option C is correct.