In the problem t is a real number and P x y is the point on

In the problem, t is a real number and P = (x, y) is the point on the unit circle that corresponds to t. Find the exact value of the indicated trigonometric function of t.

(-(squareroot 21)/5 , 2/5) Find Cot

Anserw Choice:

A) - (square root 21)/2 B) (square root 21)/ 5 C) 2/5 D) -5/2

My anserw is not here so i am wondering if the anserw choices are wrong? My anserw is (-(squareroot 21)/5

Solution

Point (x, y) = (-(squareroot 21)/5 , 2/5)

cot(t) = x/y = -sqrt(21)/5 / 2/5

( 5 gets cancelled)

cot(t) = -sqrt(21)/2

OPtion A