Question

A triangle has sides A, B, and C. Sides A and B are of lengths `5` and `3`, respectively, and the angle between A and B is `(3pi)/4`. What is the length of side C?

Answer 1

`C=7.43`

Explanation:

As per law of cosines
`C^2=A^2+B^2-2Atimes Btimescos(theta)` where `A=5;B=3 and theta=(3pi)/4`
or
`C^2=5^2+3^2-2times5times3timescos((3pi)/4)`
or
`C^2=25+9-30times(-0.707)`
or
`C^2=34+21.21`
or
`C^2=55.21`
or
`C=sqrt55.21`
or
`C=7.43`