2012 · Q75
In the figure EC is parallel to AB, angle ECD = 70 degrees and angle BDO = 20 degrees. What is angle OBD equal to? (O is the intersection of AB and CD.)
Elementary MathematicsGeometry
- A20 degrees
- B30 degrees
- C40 degrees
- D50 degrees
Explanation
Corresponding angles give angle AOD = 70 degrees, so angle BOD = 110 degrees; in triangle BOD, angle OBD = 180-110-20 = 50 degrees.