text: secant function? let theta be an angle in standard position with a point p9x,y) on the terminal side distance of r equals the square root of quantity x squared plus y squared from the origin (r is not equal to zero). then the secant function is defined by?   i come up with r/x , x can not = 0. am i correct here? yes, that is right. the secant function 'sec(θ)' gives the reciprocal of the cosine function 'cos(θ)'. we know that  cos(θ) = x/r (as per your case)  thus,   sec(θ) = 1/cos(θ) = r/x  hence proved.