Question

-7cos2a, sina=0.5 a - альфа

Answer 1

Ответ:

-7cоs2a=-7(1-2$sin^{2}$a)=-7(1-0,5)=-3,5

Answer 2

It seems like you have an equation involving trigonometric functions, specifically involving the cosine and sine functions. You've also mentioned that sin(a) = 0.5. Let's solve for a (alpha):

Given: -7cos(2a) sin(a) = 0.5

First, let's solve for cos(2a) using the identity:

cos(2a) = 1 - 2sin^2(a)

We already know sin(a) = 0.5, so:

cos(2a) = 1 - 2(0.5)^2 cos(2a) = 1 - 2(0.25) cos(2a) = 1 - 0.5 cos(2a) = 0.5

Now, we have:

-7cos(2a) = -7(0.5) -7cos(2a) = -3.5

So, the value of -7cos(2a) when sin(a) = 0.5 is -3.5.

If you have any more specific questions or need further clarification, please feel free to ask.