Simplification: (tan10 ° − 3)•cos10° sin50°．

Simplification: (tan10 ° − 3)•cos10° sin50°．

(tan10°−
3)•cos10°
sin50°
=(sin100−
3cos100)•cos100
cos100•sin500
=2(1
2sin100−
Three
2cos100)
sin500
=2(sin100cos600−cos100sin600)
sin500
=2sin(−500)
sin500=-2

Simplification: cos10 ° (tan10 ° - radical 3) / sin50 °

=cos10(tan10-√3)/sin(60-10)
=sin10-√3cos10/(√3cos10-sin10/2)
=-2

Calculation: (sin20 ° - sin40 °) / (cos20 ° - cos40 °)

sin α-sin β=2cos[(α+β)/2]×sin[(α-β)/2]
cos α-cos β=-2sin[(α+β)/2]×sin[(α-β)/2]
(sin20°-sin40°)÷(cos20°-cos40°)
= (sin40°-sin20°)÷(cos40°-cos20°)
= {2cos[(40+20)/2]×sin[(40-20)/2]} ÷{-2sin[(40+20)/2]×sin[(40-20)/2] }
= - cos30sin10÷sin30cos10
= -√3tan10

（cos20°-cos40°)/(sin20°-sin40°）=?

（cos20°-cos40°)/(sin20°-sin40°）=[cos(30°-10°)-cos(30°+10°)]/[sin(30°-10°)-sin(30°+10°)] =[(cos30°cos10°+sin30°sin10°)-(cos30°cos10°-sin30°sin10°)]/[(sin30°cos10°-cos30°sin10°)-(sin30°cos10°-cos30°sin10°)]=（2sin30sin10°)/（-2cos30sin10°)=-tan30°=-√3/3
Adopt it

The value of cos40 ° cos20 ° - sin40 ° sin20 ° is equal to______ .

cos40°cos20°-sin40°sin20°=cos（20°+40°）=cos60°=1
Two
So the answer is 1
2．

Evaluation: (sin20 ° - sin40 °) / cos20 ° - cos40 °)

(sin20°-sin40°)/(cos20°-cos40°)=(sin20°-sin40°)/(sin70°-sin50°)=2sin[(20-40)/2]cos[(20+40)/2]/2sin[(70-50)/2]cos[(70+50)/2]=sin(-10)cos30/sin10cos60=-sin10cos30/sin10cos60=-sin60/cos60=-tan60=...

Cot20 degree cos10 degree + root 3 times sin10 degree Tan 70 degree - 2cos40 degree =?

cot20°cos10°+√3sin10°tan70°-2cos40°
=cos10°cos20°/sin20°+√3sin10°sin70°/cos70°-2cos40°
=cos10°cos20°/2sin10°cos10°+√3sin10°cos20°/sin20°-2cos40°
=cos20°/2sin10°+√3sin10°cos20°/2sin10°cos10°-2cos40°
=cos20°/2sin10°+√3cos20°/2cos10°-2cos40°
=(cos10°cos20°+√3sin10°cos20°)/2sin10°cos10°-2cos40°
=2cos20°(√3sin10°/2+cos10°/2)/sin20°-2cos40°
=2cos20°(sin10°cos30°+cos10°sin30°)/sin20°-2cos40°
=2cos20°sin40°/sin20°-2cos40°
=4sin20°cos²20°/sin20°-2cos40°
=4cos²20°-2cos40°
=2(2cos²20°-1)-2cos40°+2
=2cos40°-2cos40°+2
=2

Simplification: cos20 degree cos35° 1−sin20°．

∵cos10°=sin80°>sin10°，∴cos20°cos35°1−sin20°=cos20°cos35°(cos10°−sin10°)2=cos20°cos35°(cos10°−sin10°)=cos20°cos35°•2sin(45°−10°)=cos20°22•2sin35°cos35°=2•cos20°sin70...

tan70°+tan50°- The value of 3tan70 ° tan50 ° is equal to () A. Three B. Three Three C. − Three Three D. − Three

From Tan 120 ° to tan (70 ° + 50 °)
=tan70°+tan50°
1−tan70°tan50°=-tan60°=-
3，
Tan 70 ° and Tan 50 ° are obtained=-
3+
3tan70°tan50°，
Then Tan 70 ° and Tan 50 °-
3tan70°tan50°=-
3．
Therefore, D is selected

Tan70 degree + tan50 degree - radical 3 * tan70 Degree * tan50 degree is equal to

70°+50°=120°,
Tan70 ° + tan50 ° - root number 3tan70 ° tan50 ° = tan120 ° (1-tan70 ° tan50) - root number 3tan70 ° tan50
=-Root 3 (1-tan70 ° tan50) - Radix 3tan70 ° tan50
=-Root number 3 + root number 3tan70 ° tan50 - root number 3tan70 ° tan50
=-Radical 3