Question

如图1,在三角形ABC中,角A=45度,AC=根号2,AB=根号3+1,BC=?

Answer 1

BC^2=AB^2+AC^2-2AB*AC*cosA

=(√3+1)^2+(√2)^2-2*(√3+1)*√2*√2/2

=3+2√3+1+2-2(√3+1)

=6+2√3-2√3-2

=4

BC=2