Question

How do you express `tan((19pi)/5)` as a trig function of an angle in Quadrant I?

Answer 1

`- tan (pi/5)`

Explanation:

`tan ((19pi)/5) = tan (-pi/5 + 20pi/5) = tan (-pi/5 + 4pi) =`
`= tan (- pi/5) = - tan (pi/5)`
`pi/5` is an arc (or angle) in Quadrant 1.