What is the measure of ∠BCD? Enter your answer in the box. ° quadrilateral A B C D with side A B parallel to side D C and side A D paralell to side B C. angle B is 103 degrees.

The asnwer is ∠C=77°, ∠BCD = 283°

Step-by-step explanation:

According to the info or the problem angles B and C are adjacent angles of a paralellogram, so those angles are supplementary each other.

We can calculate the angle C applying the supplementary angles theory:

⇒ ∠C = 180° - ∠B = 180° - 103° = 77°.

So angle ∠C = 77°.

In the parallelogram angle B its opposite to D, so ∠D = 103°.

Doing the sumatory of the angles ⇒ ∠BCD = 103° + 77° + 103° = 283°.

We can corroborate that result its okay because the sumatory of the inner angles of a parallelogram always is 360°.

In conclusion if we add the angle ∠A = 77° (becasuse its opposite to C) to the summation ⇒ 283° + 77° = 360°.

77°

Step-by-step explanation:

Angles B and C are adjacent angles of a parallelogram, so are supplementary.

... ∠C = 180° - ∠B = 180° - 103° = 77°