Question

In figure AB perpendicular to AE, BC perpendicular AB, CE = DE and angle AED = 120
then find angle ECD
a) 80
b) 70
c) 85
d) 60
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Answer 1

Step-by-step explanation:

• Given angle AED=120 degree
• Ab is perpendicular to AE
• Therefore angle EAB=90 degree
• BC is perpendicular to AB
• Therefore angle DBA=90 degee
• From angle sum property quadrilateral ABDE we get
• Angle EAB + angle AED + angle EBD + angle DBA = 360 degree
• So 90 + 120 + angle EFB + 90 = 360 degree
• 300 + angle EDB= 360
• Or angle EDB = 360 - 300
• Or angle EDB = 60 degree
• So angle ECD = 60 degree (since similar angle)
• Also CE=DE

From base angle theorem we get

Angle EDC = angle ECD = 60 degree