9514 1404 393
Answer:
105°
Step-by-step explanation:
∠EBC = ∠EBD + ∠DBC
∠EBC = 45° + 60°
∠EBC = 105°
__
The diagonal of the square bisects the 90° corner angle, so the portion of interest is 90°/2 = 45°.
An equilateral triangle has all three angles the same: 180°/3 = 60°.
