Question

In the picture lines AB and CD are parallel. Find the measures of the following angles. Explain your reasoning.

Answer 1

Answer/Step-by-step explanation:

1. <ABC and <BCD are alternate interior angles. Alternate interior angles are equal, therefore, since m<ABC = 38°, then m<BCD = 38°

2. m<ECF = m<BCD (corresponding angles)

m<ECF = 38° (substitution)

3. m<DCF + m<ECF = 180° (linear pair)

m<DCF + 38° = 180° (substitution)

m<DCF = 180° - 38° (Subtraction property of equality)

m<DCF = 142°