Triangle A B C is shown with its exterior angles. Line B A extends through point D. Line A B extends through point E. Line A C extends through point F. Which angle's measure is equal to the sum of the measures of ∠BAC and ∠BCA?

∠CBE

Step-by-step explanation:

Find the diagram attached

Using the exterior property of a triangle which states that the sum of interior angles of a triangle is equal to the exterior angle.

Given the following from the diagram

Interior angles are ∠BAC and ∠BCA

Exterior angle = <CBE = a+b

Using the law above,

∠BAC + ∠BCA = ∠CBE

Hence the angle's measure that is equal to the sum of the measures of ∠BAC and ∠BCA is ∠CBE