The bisectors divide an equilateral triangle in

Angle, which can be drawn by using ruler and compass, should be multiple of $15°$.

To draw an angle of $90°$ using a ruler and compass, we bisect the angle between $60°$ and $120°$.

An angle has an interior as well as an exterior region.

Protractor is used to mark off equal lengths, but does not measure them, also used to draw arcs and circles.