Question

3 cos(360-альфа)-3sin(270-альфа). если cos альфа =0,7

Answer 1

что тут думать-то??при 360 функция не меняется,при 270-меняется
будет:
3cosA+3cosA=6cosA=6*0,7=4.2 

Answer 2

3 cos(360-а)-3sin(270-а)=3 cos(2pi-а)-3sin(3pi/2-а)=3cos(-a)-3sin(pi-a)=3cos(a)-3sin(a)

Найдем sina

sin$sina=\sqrt{1-cos^2a}=\sqrt{1-0,49}=\sqrt{0,51}$

 

$3cos(a)-3sin(a)=3(0,7-\sqrt{0,51})$

Answer 3

First, let's use the trigonometric identity cos(360 - α) = cos(α) and simplify the first term:

3 cos(360 - α) = 3 cos(α)

Next, let's use the trigonometric identity sin(270 - α) = cos(α) and simplify the second term:

3 sin(270 - α) = 3 cos(α)

Now we can substitute cos(α) = 0.7 into both terms:

3 cos(α) - 3 sin(270 - α) = 3(0.7) - 3 cos(α)

= 2.1 - 3(0.7)

= 2.1 - 2.1

= 0

Therefore, the value of the expression is 0.