Question

question 8 of 10
what is cos 45°?
a. 1
b. \frac{1}{\sqrt{2}}
c. \frac{1}{2}
d. \sqrt{2}

Explanation:

Step1: Recall the cosine formula

In a right - triangle, $\cos\theta=\frac{\text{adjacent side}}{\text{hypotenuse}}$.

Step2: Identify the sides for $\theta = 45^{\circ}$

For the given right - triangle with $\theta = 45^{\circ}$, the adjacent side to the $45^{\circ}$ angle is $1$ and the hypotenuse is $\sqrt{2}$.
So, $\cos45^{\circ}=\frac{1}{\sqrt{2}}$.

Answer:

B. $\frac{1}{\sqrt{2}}$