Question

Find the length of a if the measure of angle a equals 62 degrees b = 15, and c = 21.

Answer 1

we know that
applying the law of cosines
a²=b²+c²-2*b*c*cos A

in this problem
A=62°
b=15
c=21
so
a²=15²+21²-2*15*21*cos 62°-----> a²=370.23-----> a=19.24

the answer is
a=19.24