What are sin x, tan x, cot x, if 180

The angle x is in the 3rd quadrant, so the value of the
function sine is negative, but the values of teh functions tangent and cotangent are
positive.

We'll apply the fundamental formula of
trigonometry:

(sin x)^2 + (cos x)^2 
=1

(sin x)^2 = 1  - (cos
x)^2

(sin x)^2 = 1  -
(-4/5)^2

(sin x)^2 = 1 -
16/25

(sin x)^2 = 9/25

sin x =
-3/5

tan x = sin x/cos x

tan x
= -3/5/-4/5

sin x = -3/5, tan x = 3/4 and cot
x = 4/3