Daniel B. answered 02/09/24
Experienced STEM Tutor with M.S. in Chemical Engineering
Going back to the unit circle, remember that cos(θ) represents the x-value for a value on the circle and sin(θ) represents the y-value. So, reflect the angle across the x-axis and find your angle for the equivalent y-value, then do the same across the y-axis for the x-value. Hope this helps!