Please help to calculate: can't use calculator Oh, can only simplify the evaluation: sin20 ° ^ 2 + cos80 ° ^ 2 + Radix 3 * cos20 ° * cos80 °, Good, fast, right again bonus!

Please help to calculate: can't use calculator Oh, can only simplify the evaluation: sin20 ° ^ 2 + cos80 ° ^ 2 + Radix 3 * cos20 ° * cos80 °, Good, fast, right again bonus!

The original formula = sin20 ^ 2 + sin20 ^ 2 + Radix 3sin20 × cos20 = 1 - cos40 + Radix 3 / 2 × sin40 Cell phone calls too slow Go back to it

Sin squared 20 ° + cos squared 80 ° + Radix 3sin20 ° cos80 °

Sum and difference of product: √ 3 * sin20cos80 = (√ 3 / 2) (sin100-sin60) = (√ 3 / 2) sin80-3 / 4 inversely, the formula of double angle is used as follows: sin 2 (20) + cos 2 (80) = (cos80) 2 + (cos70) 2 = (1 / 2) · [cos160 + 1 + cos140 + 1] = 1 - (1 / 2) · (cos40 + cos20

Calculation question (sin? 60 ° - 2sin60 ° + 1) + absolute value 1-3tan30 ° under radical sign

simple form
=√(sin60°-1)²-l1-3×√3/3l
=√(√3/2-1)²-l1-√3l
=1-√3/2-(√3-1)
=1-√3/2-√3+1
=2-3√3/2

The absolute value of cubic root - 8-1 - root 2 + root (- 3) - root 4

The absolute value of cubic root - 8-1 - root 2 + root (- 3) - root 4
=|³√-8-1-√2|+√（-3）^2-√4
=|-2-1-√2|+3-2
=2+1+√2+3-2
=4+√2

What is the result of the absolute value of 3-π + the radical sign (π-4) 2?

Absolute value of 3 - π + radical sign (π - 4) 2
=π-3+π-4
=2π-7

Divide (1 / cos20) by (radical 3 / sin20) It's a mistake. It's a minus sign in the middle, not a division

After merging, the denominator changes from 1 / 2 sin40 to - 2 sin40, so the final result is - 4
(1 / cos20) - (radical 3 / sin20)
=Sin20 / sin20cos20 - (radical 3) * cos20 / sin20cos20
=2 [(1 / 2) sin20 - (radical 3 / 2) cos20] / sin20cos20
=2sin(20-60)/1/2sin(20+20)
=-2sin40 / 1/2sin40
=-4

1. (2cos50 ° + sin20 °) / cos20 ° is equal to? 2. Sin (π / 12) - radical 3cos (π / 12) is equal to what!

In 1, 2cos50 ° + sin20 ° = 2cos (60-10) + sin (30-10) = 2 [(1 / 2) cos10 + ((root 3) / 2) sin10] + (1 / 2) cos10-sin10 ((root 3) / 2) = root 3 * [(root 3 / 2) cos10 - (1 / 2) sin10] = root 3 * (cos30cos10-sin30sin10) = root 3 * cos20

(tan10 ° - radical 3) * (sin80 ° / cos40 °)

(tan10°-√3)*（sin80°/cos40°)=(tan10°-√3)*（sin80°/cos40°)=(sin80/cos40)(cot80-√3)=(sin80/cos40)*(cos80/sin80)-(sin80/cos40)*√3 =cos80/cos40-√3sin80/cos40 =-(√3sin80-cos80)/cos40=-2(√3/2*s...

Evaluation: cos40 degrees * (1 + Radix 3 * Tan 10 degrees)

Cos 40 degrees * (1 + root 3 * Tan 10 degrees)
=(cos40 degree / cos10 degree) * (cos10 degree + Radix 3 * sin10 degree)
=(cos40 degrees / cos10 degrees) * 2 (sin30 degrees * cos10 degrees + cos30 degrees * sin10 degrees)
=(cos40 degree / cos10 degree) * 2 * sin 40 degree
=Sin80 degree / cos10 degree = 1
High school textbooks above the problem of the original example solution!

(1 + root 3 times Tan 10 degrees) times cos 40 degrees is equal to what To process

=2(sin30°+cos30°tna10°)cos40°
=2(sin30°+cos30°sin10°/cos10°)cos40°
=2sin(30°+10°）cos40°/cos10°
=2sin40°cos40°/ cos10°
=sin80°/cos10°
=cos10°/cos10°
=1