Question

Find BC.law of cosine 4A. 29 inB. 22.5 inC. 30 inD. 28 in

Answer 1

Use the law of cosine as the statement suggest you:

`BC^2=AB^2+AC^2-2(AB)(AC)\cos(A)`

Replace and solve:

`BC^2=19^2+12^2-(2*19*12*\cos(138))`
`BC^2=843.87`
`BC=√(843.87)`
`BC=29.05`