△ABC中,sinA=3/5,sinB=5/13,则sinC等于多少?_数学解答

△ABC中,sinA=3/5,sinB=5/13,则sinC等于多少?

人气：353 ℃　时间：2020-07-10 20:37:33

解答

△ABC中,sinA=3/5,sinB=5/13,
sinA>sinB 所以A>B
(1)A为锐角时
cosA=4/5 cosB=12/13
sinC=sin(A+B)
=sinAcosB+cosAsinB
=36/65+20/65
=56/65
(2) A为钝角时
cosA=-4/5 cosB=12/13
sinC=sin(A+B)
=sinAcosB+cosAsinB
=36/65-20/65
=16/65