Answers

  • Brainly User
2015-11-17T02:07:59+08:00
If BD = DC, then 70 degrees is a base angle of Isosceles ΔBCD

∠ BCD and ∠CBD are base angles.  Therefore, each base angle measures 70 degrees.

To find the third angle ∠BDC:

m∠BDC = 180 - [ m∠BCD + m∠CBD ]
m∠BDC = 180° - [ 70° + 70° ]
m∠BDC = 180° - 140°
m∠BDC = 40° 

∠BDC and ∠ADB are supplementary angles.  To find the measure of ∠ADB:
m∠ADB = 180° - m∠BDC
m∠ADB = 180° - 40°
m∠ADB = 140° 

The degree measure of ∠ADB is 140°

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