For the right triangle shown in the picture, recall the trigonometric identity of the cosine function:
[tex]\cos (B)=\frac{a}{c}[/tex]
Isolate a from the equation:
[tex]a=c\cdot\cos (B)[/tex]
Substitute for c=6.3 and B=43.8°:
[tex]a=6.3\cos (43.8)[/tex]
Use a calculator to evaluate the expression:
[tex]\begin{gathered} a=4.547089437\ldots \\ \approx4.6 \end{gathered}[/tex]
