Question

在三角形ABC中,A、B、C是三角形的三个内角,a、b、c是三内角对应的三边,已知b方+c方-a方=bc.(1)求角..

Answer 1

(1)b^2+c^2-a^2=bc

=>cosA=(b^2+c^2-a^2)/(2bc)=1/2,A∈(0,π)

=> A=π/3

(2)(sinA)^2+(sinB)^2=(sinC)^2

=>a^2+b^2=c^2

=>C=π/2

由(1)知B=π/2-π/3=π/6