Question

Найти cos2 a если sin a =1/2

Answer 1

Cos2a = 1-2sin²a = 1-2*(1/2)² = 1-2*1/4 = 1-1/2 = 1/2.

Answer 2

To find the value of cos^2(a) given that sin(a) = 1/2, we can use the trigonometric identity:

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

Since sin(a) = 1/2, we can substitute it into the identity:

cos^2(a) + (1/2)^2 = 1 cos^2(a) + 1/4 = 1

Now, isolate cos^2(a) by moving 1/4 to the other side:

cos^2(a) = 1 - 1/4 cos^2(a) = 3/4

So, cos^2(a) is equal to 3/4.