# Math Help - Find Length a

1. ## Find Length a

In ΔABC, sin A = 1/4, sin B = 1/8, and b = 20. What is the length of a?

Do I apply the law of sines here?

2. Try the law of sines.

$\frac{sinA}{a}=\frac{sinB}{b}$

$a=\frac{bsinA}{sinB}$

The law of cosines is used when we have angle, side, angle. Like in the diagram:

3. ## ok.........

Originally Posted by galactus
Try the law of sines.

$\frac{sinA}{a}=\frac{sinB}{b}$

$a=\frac{bsinA}{sinB}$

The law of cosines is used when we have angle, side, angle. Like in the diagram:
I knew it. Thanks!