Bisector of plane (acute/obtuse bisector)

In a triangle ABC, internal bisector of angleABC and external bisector of angleACB meet in D. Which one of the following is true ?

Angle Bisector

Formula and Methods to determine acute and obtuse angle bisector?

Shortcut method to determine acute and obtuse angle Bisectors

Angle Bisectors

Bisector of the plane containing origin

The bisector of the acute angle formed between the lines 4x - 3y + 7 = 0 and 3x - 4y + 14 = 0 has the equation