1. B=60度 cosB*+sinB*=1 sinB*=7/16
cosA/sinA+cosC/sinC
=给我图吧
高一数学三角函数题1
由sina=4/5,(-π/2<a<π/2)
sina^2+cosa^2=1
可得出cosa=3/5
tana=4/3
tan(a+π/4)=(tana+tanπ/4)/(1-tanaπ/4)=(7/3)/(-1/3)=-7
1. B=60度 cosB*+sinB*=1 sinB*=7/16
cosA/sinA+cosC/sinC
=给我图吧
由sina=4/5,(-π/2<a<π/2)
sina^2+cosa^2=1
可得出cosa=3/5
tana=4/3
tan(a+π/4)=(tana+tanπ/4)/(1-tanaπ/4)=(7/3)/(-1/3)=-7