Respuesta :

Given:

cos(2t) = 0.8

Take the cos⁻' of both-side of the equation.

cos⁻' cos(2t) = cos⁻'(0.8)

2t = cos⁻'(0.8)

Calculate the value of the right- hand side with your calculator in radians.

2t =0.6435

Divide both-side of the equation by 2

t ≈ 0.32