sina=(4-2m)/(m+5),cosa=(m-3)/(m+5)且a是第四象限角求tana

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sina=(4-2m)/(m+5),cosa=(m-3)/(m+5)且a是第四象限角求tana
sina=(4-2m)/(m+5),cosa=(m-3)/(m+5)且a是第四象限角求tana

sina=(4-2m)/(m+5),cosa=(m-3)/(m+5)且a是第四象限角求tana
a是第四象限角
sina0
且(sina)^2+(cosa)^2=1
[(4-2m)/(m+5)]^2+[(m-3)/(m+5)]^2=1
(4-2m)^2+(m-3)^2=(m+5)^2
4m^2-16m+16+m^2-6m+9=m^2+10m+25
4m^2-32m=0
m=0,m=8
代入sina=(4-2m)/(m+5)和cosa=(m-3)/(m+5)
则m=8符合sina0
所以sina=-12/13,cosa=5/13
tana=sina/cosa=-12/5