解方程 sinx=3siny x+y=120°

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解方程 sinx=3siny x+y=120°
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解方程 sinx=3siny x+y=120°
解方程 sinx=3siny x+y=120°

解方程 sinx=3siny x+y=120°
sin(120-y)=3sin(y)
sin120cosy-sinycos120=3siny
√3/2 cosy+1/2siny=3siny
√3/2 cosy=5/2siny
√3/5=tany
y=19.1° x=100.9° h或者sinx=sin(120°-y)=sin120°cosy-cos120°siny=(根号3)(cosy)/2+(siny)/2=3siny
得(根号3)(cosy)/2=5(siny)/2
两边同时平方化简得3cos²y=25sin²y
带入cos²y+sin²y=1
得28sin²y=3,28cos²y=25

sinx=sin(120°-y)=sin120°cosy-cos120°siny=(根号3)(cosy)/2+(siny)/2=3siny
得(根号3)(cosy)/2=5(siny)/2
两边同时平方化简得3cos²y=25sin²y
带入cos²y+sin²y=1
得28sin²y=3，28cos²y=25

sin(120-y)=3sin(y)
sin120cosy-sinycos120=3siny
√3/2 cosy+1/2siny=3siny
√3/2 cosy=5/2siny
√3/5=tany
y=19.1° x=100.9°

解方程 sinx=3siny x+y=120° x+y=pai/3,sinx*siny的最小值在线 已知sinx+siny=1/3,sinx-siny的最小值已知sinx+siny=1/3,sinx-已知sinx+siny=1/3,sinx-siny的最小值是 证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y) 若3sinx*2+2siny*2=1 且3(sinx+cosx)*2+2(siny+cosy)*2=1求cos(2x+2y) 证明sin(x+y)sin(x-y)=sinx-siny sinx-siny=1/3,cosx-cosy=2/3,sin(x+y)=? cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)=? cosx-cosy=1/2,sinx-siny=1/3,sin(x+y)=RT 已知cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)= sinx+cosy=1/3 cosx+siny=1/6 则sin(x+y)=?RT sinx-siny=-√3/3 cosx-cosy=-1/3 则cos(x-y) 已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y) cosx-cosy=4/1,sinx-siny=3/1求cos(x-y) sinx+cosy=1/3 cosx+siny=1/6 则 sin(x+y)? sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值. sinx+siny=1/4,cosx+cosy=1/3求tan(x-y) 若cosx*cosy+sinx*siny=1/3 ,则cos(2x-2y)=?