By Team Aakash Byju's | 8th December 2022
BD > BA
BA > BD
BA = BD
BD = CD
The visualisation of the given case is shown below:
Since the line AD bisects ∠BAC, it is called the angular bisector of △ABC.
∴ ∠BAD = ∠CAD
We know that the external angle of a triangle is the sum of the opposite internal angles. So, in △ADC
∠ADB = ∠ACD + ∠CAD
=> ∠ADB > ∠ACD or ∠ADB > ∠CAD
So we know that ∠BAD = ∠CAD, and ∠ADB > ∠CAD. Thus, we can write:
∠ADB > ∠BAD
Therefore, in △ABD, ∠ADB > ∠BAD. Also, we know that, in a triangle, the greater angle has the longer side opposite to it.
The side opposite ∠ADB is BA
The side opposite ∠BAD is BD
Thus, ∠ADB > ∠BAD => BA > BD