Question

If m∠ABC = 80°, what is m∠DBC? Justify your reasoning.

a- Using the Angle Addition Postulate, 20 + m∠DBC = 80. So, m∠DBC = 60° using the
subtraction property of equality.
b- Using the Angle Addition Postulate, 20 + 80 = m∠DBC. So, m∠DBC = 100° using the
addition property of equality.
c- Using the addition property of equality, 20 + 80 = 100, so m∠DBC = 100°.
d- Using the subtraction property of equality, 80 − 20 = 60, so m∠DBC = 60°.

Answer 1

Answer:

a- Using the Angle Addition Postulate, 20 + m∠DBC = 80. So, m∠DBC = 60° using the

subtraction property of equality.

Step-by-step explanation:

ABD+ DBC = ABC  by the angle addition postulate

20 + DBC =  80

Subtract 20 from each side, using the subtraction property of equality

20+DBC-20 = 80-20

DBC = 60

Answer 2

Answer:

60

Step-by-step explanation: