find an equation of the line passing throug (2,6) and is inclined at an angle 60 degrees counterclockwise from the horizontal

Answer 1

You should have learned that the slope of a line is equal to the tangent of the angle that line makes with the x-axis

so slope = tan 60° = √3/1 = √3

so the equation is:
y - 6 = √3(x - 2)
y = √3 x + 6 - 2√3