Answer:
135 degrees
Step-by-step explanation:
- Angle CBD is the sum of angle ABC and angle ABD, so we find these first
- An Isosceles triangle has 2 equal sides and 2 equal angles
- Isosceles triangle theorem tells us that the 2 equal angles are respectively opposite the equal sides
- Since triangle ABC has sides AB=AC, then angle ACB = angle ABC
- So knowing that angles of triangle add up to 180, then
- Now we do the next triangle to get ABD
- Since triangle ABD has sides AB=BD, then angle BDA = angle BAD
- So knowing that angles of triangle add up to 180, then
- Now we said, angle CBD is the sum of angle ABC and angle ABD, so