A section of a roller coaster track forms a parallelogram ABCD.

Question

If m∠ABC = 72°, what is m∠DAB?
Responses
A 144°144°
B 108°108°
C 216°216°
D 72°

Answer 1

Since opposite angles in a parallelogram are congruent, we know that m∠ABC = m∠CDA = 72°.

Therefore, m∠DAB + m∠CDA = 180° (since they form a linear pair).

Substituting in 72° for m∠CDA, we get:

m∠DAB + 72° = 180°

Subtracting 72° from both sides gives:

m∠DAB = 108°

So, choice B (108°) is the correct answer.