Daniel B. answered 12/14/20
A retired computer professional to teach math, physics
The length of vector (5, -9) is
sqrt(5² + 9²) = sqrt(146)
By definition of the trigonometric functions
sin(θ) = -9/sqrt(146)
cos(θ) = 5/sqrt(146)
tan(θ) = -9/5
csc(θ) = -sqrt(146)/9
sec(θ) = sqrt(146)/5
cot(θ) = -5/9