Question

Найдите 16cos2a, если cos a= 0,5Помогите пожалуйста, я в этом плохо шарю

Answer 1

cos2a=cos^2(a)-sin^2(a). cos^2(a)+sin^(a)=1, =>cos2a=2cos^2(a)-1
16(2cos^2(a)-1) подставляем 0,5 вместо cosa и получаем 16(2*0,25-1)=-8 

Answer 2

Calculating 16cos(2a) when cos(a) = 0.5

To find the value of 16cos(2a) when cos(a) = 0.5, we can use the double-angle identity for cosine, which states that cos(2a) = 2cos^2(a) - 1. We can then substitute the given value of cos(a) into this formula to find the value of cos(2a), and then multiply by 16 to find 16cos(2a).

Solution

Using the double-angle identity for cosine: cos(2a) = 2cos^2(a) - 1

Given that cos(a) = 0.5, we can substitute this value into the formula: cos(2a) = 2(0.5)^2 - 1 cos(2a) = 2(0.25) - 1 cos(2a) = 0.5 - 1 cos(2a) = -0.5

Now, to find 16cos(2a), we simply multiply the value of cos(2a) by 16: 16cos(2a) = 16 * (-0.5) 16cos(2a) = -8

So, 16cos(2a) = -8 when cos(a) = 0.5.