(a, 2b) is the mid-point of the line segment joining the points (10, $$-$$ 6) and (k, 4). If a $$-$$ 2b = 7, then what is the value of k?

What is the acute angle between the lines represented by the equations y $$-$$ $$\sqrt 3 $$x $$-$$ 5 = 0 and $$\sqrt 3 $$y $$-$$ x + 6 =0 ?

The points (a, b), (0, 0), ($$-$$a, $$-$$b) and (ab, b²) are

The angle between the lines x + y $$-$$ 3 = 0 and x $$-$$ y + 3 = 0 is $$\alpha$$ and the acute angle between the lines x $$-$$ $$\sqrt 3 $$y + 2$$\sqrt 3 $$ = 0 and $$\sqrt 3 $$x $$-$$ y + 1 = 0 is $$\beta$$. Which one of the following is correct?