Question

A triangle has sides A, B, and C. Sides A and B are of lengths `5` and `2`, respectively, and the angle between A and B is `(3pi)/8`. What is the length of side C?

Answer 1

`C=4.62`

Explanation:

As per law of cosines
`C^2=A^2+B^2-2Atimes Btimescos(theta)` where `A=5;B=2 and theta=(3pi)/8`
or
`C^2=5^2+2^2-2times5times2timescos((3pi)/8)`
or
`C^2=25+4-20times(0.383)`
or
`C^2=29-7.65`
or
`C^2=21.35`
or
`C=sqrt21.35`
or
`C=4.62`