3 times the square of sin20 minus 1 times the square of cos20 plus the square of 64sin20 (20 is degree)

3 times the square of sin20 minus 1 times the square of cos20 plus the square of 64sin20 (20 is degree)

3/(sin20)^2 - 1/(cos20)^2 + 64(sin20)^2
=[3(cos20)^2-(sin20)^2]/(sin20cos20)^2 + 64(sin20)^2
=[(3/4)(cos20)^2-(1/4)(sin20)^2]/[(sin20cos20)^2/4] + 64(sin20)^2
=[(√3/2)cos20+(1/2)sin20][(√3/2)cos20-(1/2)sin20]/[(sin40)^2/16] + 32*[2(sin20)^2]
=16cos(30-20)cos(30+20)/(sin40)^2 + 32[2(sin20)^2-1+1]
=16sin80sin40/(sin40)^2 + 32*(-cos40+1)
=32cos40(sin40)^2/(sin40)^2 - 32cos40 +32
=32cos40 - 32cos40 +32
=32
I pressed it for you with a calculator
The result was 32
2cos50 + sin20 / cos20
Sum difference product formula:
sina+sinb=1/2sin[(a+b)/2]cos[(a-b)/2]
cosa+cosb=1/2cos[(a+b)/2]cos(a-b)/2]
（2cos50º+sin20º）/cos20º
=（cos50º+sin40º+sin20º)/cos20º
=(cos50º+2sin30ºcos10º)/cos20º
=(cos50º+cos10º)/cos20º
=2cos30ºcos20º/cos20º
=2*√3/2
=√3
The value of sin 20 ° cos 20 ° cos 40 ° is calculated
sin20°cos20°cos40°/cos10°
=(1/2)sin40°cos40°/cos10°
=(1/4)sin80°/cos10°
=(1/4)sin80°/sin80°
=1/4
The original formula (2cos10-sin20) / cos20 = (cos10 + cos10-sin20) / cos20 = [cos10 + (cos10-cos70)] / cos20 = [cos10 + cos (40-30) - cos (40 + 30)] / cos20=[
It is known that y-m and Z-M (M is a constant) are in positive proportion, and Z is a positive proportion function of X. try to judge the functional relationship between Y and X
Let y-m = K1 (Z-M);
z=k2x
Substituting z = k2x in (2) into (1), we get the following result:
y-m=k1(k2x-m)=k1k2x-k1m
So y = k1k2x-k1m + M
The principal is a linear function of the meridian
(both K1 and K2 are not zero)
Linear function
Take any two different numbers from 1, 2, 3, 4, 9, 18 as the base and true number of a logarithm, and get the number of different logarithms
When the base number is 1, the logarithm is 0, so the logarithm can only be 0. When the base number and the true number are not 1, there is a (upper 2, lower 5) = 5X4 = 20, a table
1. If the function y = (2 + m) x is a positive proportional function, then the value of the constant M is
Wrong number, y = (2 + m) XM & sup2; - 3 is a positive proportion function, and the value of M is obtained
. take the formula apart, y = 2m ^ 2 * x + m ^ 3-3. The positive proportion is that the coefficient of term x is positive, and the other terms do not exist, m ^ 3-3 = 0, M = 3 ^ (1 / 3)
m2-3=-1 m=+-1
The sum of these logarithms is 729
Let the divisor be A1 A2 A3 A4______
lga1+lga2+______ +lgan=lg(a1*a2*a3*_____ *an)=729
It's not hard, is it?
For the positive proportional function y = MX, when x increases, y increases with X, then the value range of M is ()
A. m＜0B. m≤0C. m＞0D. m≥0
∵ for the positive proportional function y = MX, when x increases, y increases with the increase of X, ∵ m > 0
How to deduce log [1 / (sinacosa)] Sina = > 1 / {- 1-log [Sina] cosa} []
log [1/(sinacosa)]sina=-log [sinacosa]sina
-1 / log [Sina] sinacosa (bottom formula) = - 1 / {log [Sina] Sina + log [Sina] cosa} = 1 / {- 1-log [Sina] cosa}
Given that the function y = (m-2) x is a positive proportional function and Y decreases with the increase of X, then the value range of M is?
RT