Question

2cos2 альфа, если cos альфа равен 0,7.

Answer 1

Cos2a=2cos²a-1
2cos2a=2(2*(0,7)²-1)=2(0,98-1)=2*(-0,02)=-0,04

Answer 2

To find the value of 2cos^2(alpha) when cos(alpha) is equal to 0.7, you first need to calculate the value of cos^2(alpha) and then multiply it by 2.

Given that cos(alpha) = 0.7, you can find cos^2(alpha) as follows:

cos^2(alpha) = (cos(alpha))^2 cos^2(alpha) = 0.7^2 cos^2(alpha) = 0.49

Now, multiply cos^2(alpha) by 2 to find the value of 2cos^2(alpha):

2cos^2(alpha) = 2 * 0.49 2cos^2(alpha) = 0.98

So, 2cos^2(alpha) is equal to 0.98 when cos(alpha) is 0.7.