Question

what statement could you write in a proof for m∠adc using the angle addition postulate as a reason?
a. m∠adc + m∠adb = m∠bdc
b. m∠adc + m∠bdc = m∠adb
c. m∠adb + m∠bdc = m∠adc
d. m∠adc + m∠adb + m∠bdc = 90

Explanation:

Step1: Recall Angle - Addition Postulate

The Angle - Addition Postulate states that if point $D$ lies in the interior of $\angle ABC$, then $m\angle ABD + m\angle DBC=m\angle ABC$. In the case of angles $\angle ADB$ and $\angle BDC$ which together form $\angle ADC$, we have $m\angle ADB + m\angle BDC=m\angle ADC$.

Answer:

B. $m\angle ADB + m\angle BDC=m\angle ADC$