Given a parallelogram ABCD such that AB=7, AC=10 ang angle BAC=36°07'. Find the length of BC.

We can use the Law of Cosines to find BC, we have

BC^2  = AC^2 + AB^2 - 2(AC)*AB)cos(BAC)

BC^2  = 100 + 49  - 2(10)(7)cos(36.07)

BC^2  = 35.83824141348     ...take the positive square root of both sides

BC = about 5.99