tanα=-√3/3所以α等于多少？ tana=√3/3,怎么求a的度数（要具体过程）
tanA=-3\u5206\u4e4b\u6839\u53f73\uff0cA\u7b49\u4e8e\u591a\u5c11\u2235\u4e3atanA = sinA/cosaA= -\u221a3/3
\u2234sinA = (-\u221a3/3)*cosA
(sinA)^2 = 1/3 * (cosA)^2
\u53c8\u2235(sinA)^2 + (cosA)^2 = 1
\u22344 * (sinA)^2 = 1
sinaA= 1/2 \u6216\u8005 -1/2
\u4f46\u56e0\u4e3atanaA< 0,\u6240\u4ee5A\u662f\u572890\u5230180\u5ea6\u4e4b\u95f4,\u6839\u636esinA = 1/2,\u53ef\u4ee5\u5f97A= 150\u5ea6.
\u56e0\u4e3atana = sina/cosa = -\u221a3/3
\u6240\u4ee5sina = (-\u221a3/3)*cosa
\u56e0\u6b64(sina)^2 = 1/3 * (cosa)^2
\u53c8\u56e0\u4e3a(sina)^2 + (cosa)^2 = 1
\u6240\u4ee54 * (sina)^2 = 1
\u6240\u4ee5sina = 1/2 \u6216\u8005 -1/2
\u4f46\u56e0\u4e3atana < 0\uff0c\u6240\u4ee5a\u662f\u572890\u5230180\u5ea6\u4e4b\u95f4\uff0c\u6839\u636esina = 1/2\uff0c\u53ef\u4ee5\u5f97a = 150\u5ea6\u3002
\u5e0c\u671b\u6709\u7528\uff0c\u8c22\u8c22\u91c7\u7eb3\u3002
tanα=一√3/3，
α=kπ+(π一π/6)
=kπ+5π/6。
α=(k-1/6)π，k∈Z.
绛旓細tana=-鈭3锛宻ina/cosa=-鈭3锛宻ina=-鈭3cosa锛屽張锛坰ina锛塣2+锛坈osa锛塣2=1锛屼唬鍏ュ嵆鍙眰鍑烘潵銆
绛旓細瑙ｏ細鈭tan伪=-鈭3 鈭次=k蟺-蟺/3 (k鏄暣鏁)鏁卻in伪=sin(k蟺-蟺/3)=sin(k蟺)*cos(蟺/3)-sin(蟺/3)*cos(k蟺)=-(鈭3/2)*(-1)^k =(鈭3/2)*(-1)^(k+1)cos伪=cos(k蟺-蟺/3)=cos(蟺/3)*cos(k蟺)+sin(蟺/3)*sin(k蟺)=(1/2)*(-1)^k銆
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绛旓細cos伪=-1/鈭(1+tan²伪)=-1/2 cot伪=1/tan伪=-鈭3/3 伪涓虹鍥涜薄闄愯鏃讹細sin伪=tan伪/鈭(1+tan²伪)=-鈭3/2 cos伪=1/鈭(1+tan²伪)=1/2 cot伪=1/tan伪=-鈭3/3
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绛旓細sin伪=-2鍒嗕箣鏍瑰彿3 sin²伪+cos²伪=1 cos²伪=1-sin²伪=1/4 (1)伪涓虹涓夎薄闄愯 cos伪=-1/2 tan伪=鈭3 (2)伪涓虹鍥涜薄闄愯 cos伪=1/2 tan伪=-鈭3,10,
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绛旓細瑙ｏ細tan伪=鏍瑰彿3 鎺ㄥ嚭 sin伪/cos伪=鏍瑰彿3锛涚敱sin2伪锛堣繖閲岀殑2鏄寚骞虫柟锛屼笅鍚岋級+cos2伪=1寰 cos2伪-3cos2伪=1锛岃В寰梒os伪=+ -鍙堝洜涓合<伪<3/2蟺锛屾墍浠os伪=-0.5锛泂in伪=-鏍瑰彿3*0.5锛岀患涓婏紝cos伪-sin伪=锛1-鏍瑰彿3锛*0.5.
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