Respuesta :

Answer:

If one uses the cosine rule:       c^2 = a^2 + b^2 - 2 a b cos θ

3^2 = 2^2 + 4^2 - 16 cos θ

9 = 20 - 16 cos θ

cos θ = 11 / 16 = .6875

θ = 46.6 deg = 46.6 / 360 * 2 π = .813 rad

Check: 1 rad = 57.3 deg

.813 * 57.3 = 46.6 deg