Question

question 4
which angle is an acute angle?
○ $\angle abc$
○ $\angle fbd$
○ $\angle fba$
○ $\angle fbe$

Explanation:

1. ∠ABC: This is a straight angle formed by points A, B, D on a straight line, so it measures $180^\circ$, not acute.
2. ∠FBD: The right angle symbol shows ∠FBD is $90^\circ$, a right angle, not acute.
3. ∠FBA: This angle is adjacent to the right angle ∠FBD on the straight line. Its measure is $180^\circ - 90^\circ = 90^\circ$, a right angle, not acute.
4. ∠FBE: This angle is smaller than the right angle ∠FBD, so its measure is between $0^\circ$ and $90^\circ$, fitting the definition of an acute angle.

Answer:

∠FBE