Answer
$2-\sqrt 3$
Work Step by Step
$tan195^\circ =tan(150^\circ+45^\circ)=\frac{tan150^\circ +tan45^\circ }{1-tan150^\circ tan45^\circ }=\frac{(-\frac{\sqrt 3}{3})+(1)}{1-(-\frac{\sqrt 3}{3})(1)}=\frac{3-\sqrt 3}{3+\sqrt 3}\times\frac{3-\sqrt 3}{3-\sqrt 3}=\frac{12-6\sqrt 3}{6}=2-\sqrt 3$
