由正弦定理：
AB/SINC=AC/SINB
60/SINC=50/SIN30
SINC=3/5 COSC=根号下[1-(SINC)^2]=4/5或-4/5 SINB=SIN30=1/2 COSB=COS30=（根号3）/2
]在三角形中,SINA=SIN(B+C)=SINB*COSC+COSB*SINC
SINA=SIN(B+C)=1/2*(+-4/5)+（根号3）/2*(3/5)
=(3根号3+-4)/10
S三角形面积=（1/2）*ab*ac*sina
=(1/2)*60*50*(3根号3+-4)/10
=150*(3根号3+-4)