77. Find the equation of the line passing through the point $(2 ; 2)$ and making an angle of $60^{\circ}$ with the $O x$ axis.
Solution. We will use the equation of a straight line passing through a given point in a given direction (4). According to the condition, $k=\operatorname{tg} 60^{\circ}=\sqrt{3}$, therefore, the required equation of the line will be

$$
y--2=\sqrt{3}(x-2) \text { or } y=x \sqrt{ } \overline{3}+2(1-\sqrt{3}) .
$$