Question 878735
cos = -4/7
----
{{{sin(t) = sqrt(1 - cos^2(t)) = sqrt(1 - 16/49) = sqrt(33/49)}}}
sin = sqrt(33)/7 or -sqrt(33)/7
---
tan = sin/cos = sqrt(33)/4 or -sqrt(33)/4
===========
The signs depend on the quadrant.
cos = -4/7 --> Q2 or Q3