|AB|=\sqrt{(\cos\alpha -\cos\beta )^2+(\sin\alpha -\sin\beta )^2} =\sqrt{\cos^2\alpha +\sin^2\alpha+\cos^2\beta +\sin^2\beta -2\cos\alpha \cos\beta -2\sin\alpha \sin\beta } =\sqrt{2-2(\cos\alpha \cos\beta +\sin\alpha \sin\beta )} =\sqrt{2-2\cos(\...
Click here:point_up_2:to get an answer to your question :writing_hand:let a and b denote the statementsa cos alpha cos beta cos gamma
因为α -β =π ,所以α =π +β . 对A,cos α =cos (π +β )=-cos β ,故A不正确; 对B,sin α =sin (π +β )=-sin β ,故B不正确; 对C,tan α =tan (π +β )=tan β ,故C正确; 对D,sin α =sin (π +β )=-sin β ,故D不正确. 【答案】 C...