Question

A triangle has sides A, B, and C. Sides A and B are of lengths `9` and `2`, respectively, and the angle between A and B is `pi/3`. What is the length of side C?

Answer 1

`C=8.2`

Explanation:

As per law of cosines
`C^2=A^2+B^2-2Atimes Btimescos(theta)` where `A=9;B=2 and theta=(pi)/3`
or
`C^2=9^2+2^2-2times9times2timescos((pi)/3)`
or
`C^2=81+4-36times(0.5)`
or
`C^2=85-18`
or
`C^2=67`
or
`C=sqrt67`
or
`C=8.2`