Question

4cos^2a - sin^2a если sin=0,2

Answer 1

Ответ:

3.84 (но это не точно)

Пошаговое объяснение:

4cos^2a - sin^2a

cos 2a=cos^2a - sin^2a

cos 2a= 1-sin^2a

4(1-sin^2a)=4(1-0.04)=3.84

Answer 2

To find the value of the expression 4cos^2(a) - sin^2(a) when sin(a) = 0.2, we can use trigonometric identities and the given value of sin(a).

First, let's use the Pythagorean identity for sine and cosine: sin^2(a) + cos^2(a) = 1

We can solve for cos^2(a) by subtracting sin^2(a) from both sides of the equation: cos^2(a) = 1 - sin^2(a)

Now, substitute the given value sin(a) = 0.2 into the equation: cos^2(a) = 1 - (0.2)^2 cos^2(a) = 1 - 0.04 cos^2(a) = 0.96

Now that we have the value of cos^2(a), we can plug it into the original expression: 4cos^2(a) - sin^2(a) = 4(0.96) - (0.2)^2 = 3.84 - 0.04 = 3.8

So, when sin(a) = 0.2, the value of the expression 4cos^2(a) - sin^2(a) is 3.8.