Question

在△ABC中,角A,B,C的对边分别为a,b,c,∠B=60度,cosA=4/5,b=√3.

Answer 1

(1) cosA=4/5 => A=36.8699

B=60 => C=180-A-B=180-36.8699-60=83.1301

sinC=sin(83.1301)=0.9926

(2)正弦定理

a/sinA=b/sinB=c/sinC

=>c=b*sinC/sinb=1.4899

S=0.5*b*a*sinC=1.2808