Answer:
∠BEC=90°
Step-by-step explanation:
∠A=∠BCD and ∠ABC=∠D because opposite angles in a parallelogram are equal.
∠A=∠BCD=70
All angles in a quadrilateral add to 360:
∠A+∠ABC+∠BCD+∠D=360
∠ABC+∠D=360-140=220
∠ABC=∠D=110
Since ∠ABC=∠ABE+∠EBC, and ∠ABE=∠EBC (because BE is an angle bisector), ∠EBC=55.
Since ∠BCD=∠BCE+∠ECD, and ∠BCE=∠ECD (because CE is angle bisector), ∠BCE=35.
All angles in a triangle add to 180:
∠BCE+∠EBC+∠BEC=180
35+55+∠BEC=180
∠BEC=180-90
∠BEC=90°
