Question

note: triangle is not to scale. in
ight\ triangle abc above, what is the cosine of b? question help: video

Explanation:

Step1: Recall cosine formula

In a right - triangle, $\cos\theta=\frac{\text{adjacent}}{\text{hypotenuse}}$. For angle $B$, the adjacent side to angle $B$ is side $BC$ and the hypotenuse is side $AB$.

Step2: Identify side lengths

We are given that $BC = 5$ and $AB=10$.

Step3: Calculate cosine of $B$

Using the cosine formula $\cos B=\frac{BC}{AB}=\frac{5}{10}$.

Answer:

$\frac{5}{10}$