The measure of angle ABD is 20 degrees and this can be determined by using the properties of the angle bisector.
Given :
ABC = 40 and BD is the angle bisector of angle ABC.
The following steps can be used in order to determine the angle ABD:
Step 1 - According to the given data, BD is the angle bisector of angle ABC.
Step 2 - An angle bisector bisects the angle into two equal parts.
Step 3 - So, the measure of angle ABD is calculated as:
So, the measure of angle ABD is 20 degrees.