Question

which trig function is this?
cos
tan
sin

Explanation:

Step1: Recall trigonometric function definitions

In a right - triangle, $\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}$, $\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}$, and $\tan\theta=\frac{\text{opposite}}{\text{adjacent}}$.
For the given triangle, the side opposite to $\theta$ is $8$, and the hypotenuse is $15$.

Step2: Identify the function

Since $\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}=\frac{8}{15}$, the trigonometric function is $\sin$.

Answer:

$\sin$