已知$sin\alpha =\dfrac {3} {5},\alpha \in \left ( {0,\pi } \right )$,则$tan\alpha $的值等于$\left ( {\, \, \, \, \, \, } \right )$ $A、± \dfrac {4} {3}$ $B、$$\pm \dfrac {3} {4}$ $C、$$\dfrac {4} {3}$...
解析 .'sin(T-a)=-2sin-|||-T-|||-+a-|||-2.∴.sina=-2c0sa①又sin2a+c0s2a=1②,联立1-|||-2解得2/5-|||-sina=-|||-5-|||-COSQ=-|||-5或2/5-|||-sina=-|||-5-|||-√5-|||-COSQ=-|||-5故;综上,答案选择:A ...
1.化简 _ 等于()。1.化简 _ 等于()。(A) \$2 \sqrt { 3 } \sin \left( \alpha - \frac { \pi } { 3 } \right)\$ (B)1.化简 _ 等于()。(A) \$2 \sqrt { 3 } \sin \left( \alpha - \frac { \pi } { 3 } \right)\$ (B) 相关知识点: 试题来源: 解析 ...