Use the trigonometric identities to find sin x, tan x, and cot(-x), given cos x = 3/5 and x in quadrant IV

Question

Could anyone help me solve this problem? I've been stuck on it for a while.

Answer 1

Hi Jackie,

 

If angle x is in Quadrant IV, sinx and tanx will be negative.

 

if cosx = 3/5, we have a right reference triangle of 3-4-5.

then sin x = -4/5

tan x = -4/3 

 

cot(-x) = - cot x

cot x = 1/tan x

cot(-x) = - (1/(-4/3))

= 3/4