The point P(-4,9) is on the terminal arm of ∠A

(a) Find the primary trigonometric ratios (sinA, cosA, tanA) in exact values.
(b) Determine the measure of ∠A to the nearest degree.

1 answer

you have
x = -4
y = 9
r = √(x^2+y^2) = √97
Now recall that
cosθ = x/r = -4/√97
sinθ = y/r
tanθ = y/x
and so on.
(b) so use the absolute value of any of those trig functions to find the reference angle Ø. In QII you want θ=π-Ø