$\"\"$

Consider $\"\"$ .

Find angle $\"\"$ .

In a $\"\"$ :

$\"\"$

For a triangle $\"\"$ , $\"\"$ .

$\"\"$

Law of sines: \ \

$\"\"$

$\"\"$ is the altitude from a vertex to the opposite side $\"\"$ . \ \

$\"\"$

Substitute $\"\"$ .

$\"\"$

The altitude from a vertex to the opposite side $\"\"$ is $\"\"$ .