Aus Online Mathematik Brückenkurs 1

This exercise is somewhat of a trick question, because we don't need any trigonometry to solve it.

Two angles are given in the triangle (the \displaystyle \text{6}0^{\circ } angle and the right-angle) and thus we can use the fact that the sum of all the angles in a triangle is \displaystyle \text{18}0^{\circ },

\displaystyle v+60^{\circ }+90^{\circ }=180^{\circ }

which gives

\displaystyle v=180^{\circ }-60^{\circ }-90^{\circ }=30^{\circ }