Question

I want to know how I can solve this question.

Answer 1

For the right triangle shown in the picture, recall the trigonometric identity of the cosine function:

$\cos (B)=\frac{a}{c}$

Isolate a from the equation:

$a=c\cdot\cos (B)$

Substitute for c=6.3 and B=43.8°:

$a=6.3\cos (43.8)$

Use a calculator to evaluate the expression:

$\begin{gathered} a=4.547089437\ldots \\ \approx4.6 \end{gathered}$