Question

which trig function is this? cos sin tan

Explanation:

Step1: Recall trigonometric function definitions

In a right - triangle, $\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}$, $\sin\theta=\frac{\text{opposite}}{\text{hypotenuse}}$, and $\tan\theta=\frac{\text{opposite}}{\text{adjacent}}$.
Here, the side adjacent to $\theta$ is $18$ and the hypotenuse is $38$.

Step2: Match with the formula

Since we have the ratio of the adjacent side to the hypotenuse, it matches the formula for $\cos\theta$.

Answer:

cos