Question

Cos2a=0,4 знайти sin^a

Answer 1

Cos2a=1-2(sina)^2
0,4=1-2(sina)^2
2(sina)^2=1-0,4
2(sina)^2=0,6
(sina)^2=0,3
sina=√0,3 или sina= - √0,3

Answer 2

To find sin^2(a), we need to first find sin(a) using the given information. Since cos^2(a) + sin^2(a) = 1 for any angle 'a', we can use this relationship to find sin(a).

Given: cos^2(a) = 0.4

We know that cos^2(a) + sin^2(a) = 1, so:

0.4 + sin^2(a) = 1

Now, let's solve for sin^2(a):

sin^2(a) = 1 - 0.4 sin^2(a) = 0.6

Now, to find sin(a), we take the square root of sin^2(a):

sin(a) = √(0.6)

sin(a) ≈ 0.7746

So, sin^2(a) is approximately equal to 0.6, and sin(a) is approximately equal to 0.7746.