tan (−13π/6) exact value?

Answer 1

`tan-13pi/6` = tan`-7pi/6`  = tan`-pi/6`

because tan has a period of 180 degrees (repeats every 180).

So, due to fact that tan(-x) = -tan (x), a common identity that is worth knowing,

tan(-pi/6) is the same as -tan(pi/6), and -tan pi/6 = -tan 30 = -1/(root3) or -(root3)/3

so tan (-13pi/6) = -(root3)/3 as an exact value