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tAn70Cos10

原式 =cos10(tan60-tan70) =cos10(sin60/cos60-sin70/cos70) =cos10(sin60cos70-sin70cos60)/cos60cos70 =cos10sin(60-70)/(1/2)cos70 =2cos10sin(-10)/sin20 =-2cos10sin10/sin20 =-sin20/sin20 =-1 满意请采纳

tan70×cos10×(√3tan20-1) =tan70×cos10×(tan60×tan20-1) =tan70×cos10×[(sin60×sin20/cos60×cos20)-1] =tan70×cos10×(sin60×sin20-cos60×cos20)/(cos60×cos20) =tan70×cos10×[-cos(60+20)]/(cos60 ×cos20) =-tan70×cos10×cos80/(cos60×cos20) =-...

解:tan70×cos10×(√3tan20-1) =tan70×cos10×(tan60×tan20-1) =tan70×cos10×[(sin60×sin20/cos60×cos20)-1] =tan70×cos10×(sin60×sin20-cos60×cos20)/(cos60×cos20) =tan70×cos10×[-cos(60+20)]/(cos60 ×cos20) =-tan70×cos10×cos80/(cos60×cos20...

cos10/tan20+√3sin10tan70-2cos40 =cos10/cot70+√3sin10tan70-2cos40 =cos10tan70+√3sin10tan70-2cos40 =tan70(cos10+√3sin10)-2cos40 =tan70*2sin(10+30)-2cos40 =2(tan70sin40-cos40) =2(cot20sin40-cos40) =2[(cos20sin40)/sin20-cos40] =2[(...

你好 cos10°/tan20°+√3sin10°tan70°-2cos40° =cos10°cos20°/sin20°+√3sin10°sin70°/cos70°-2cos40° =cos10°cos20°/sin20°+√3sin10°cos20°/sin20°-2cos40° =2cos20°/sin20°(1/2cos10°+√3/2sin10°)-2cos40° =2cos20°/sin20°*sin(30°+10°)-2cos...

tan70°cos10°+(√3)sin10°tan70°-2cos40° =tan70﹙cos10+√3sin10﹚-2cos40 =2tan70﹙1/2cos10+√3/2sin10﹚-2cos40 =2tan70sin﹙10+30﹚-2cos40 =2cos20/sin20×﹙2sin20cos20﹚-2cos40 =4cos20-2﹙2cos20-1﹚ =2 满意请采纳

[(根3)tan20度-1]=2(√3/2tan20度-1/2)=2(cos30°tan20°-sin30°)=2(sin20°cos30°-cos20°sin30°)/cos20°=2sin(20°-30°)/cos20°=-2sin10°/cos20° ] tan70度cos10度[(根3)tan20度-1]=tan70°cos10°×(-2sin10°/cos20°)=-tan70°(2sin10°cos10°)/cos20...

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(1) sin40(sin10/cos10 - sin60/Cos60) =Sin40/(Cos10Cos60) (Sin 10 Cos60 - Cos10Sin60) =Sin40 Sin (-50)/ (Cos10 Cos60) =-Sin40 Cos40 / (Sin80 Cos 60) = - Sin80/ 2 /(Sin80 Cos 60) = - 1/(2Cos60) =-1 (2)Sin70/Cos70 Cos10 * (Sin 60/...

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