Question

cos()=0.28, 0∠∠ --2четверть. Найти cos

Answer 1

$cosa=0,28\\\\\frac{\pi}{2}$

Answer 2

To find the value of cos(2θ) given that cos(θ) = 0.28 and θ is in the second quadrant, we can use the double-angle formula for cosine:

cos(2θ) = 2 * cos^2(θ) - 1

Since cos(θ) = 0.28, we can substitute it into the formula:

cos(2θ) = 2 * (0.28)^2 - 1

Now, calculate:

cos(2θ) = 2 * 0.0784 - 1 cos(2θ) = 0.1568 - 1 cos(2θ) = -0.8432

So, cos(2θ) is approximately -0.8432.