Step-by-step explanation:
So first thing is to determine which trigonometric ratio we use here. Theta is adjacent to 5 and 8 is the hypotenuse, so we should be using Cosine.
So we set up the equation
cos θ = adj/hype
cos θ = 5/8
θ = [tex]cos^{-1} (5/8)[/tex]
θ=51.3178125...
θ=51°
