# In the parallelogram ABCD on the side BC, point E is marked so that AB = BE. Find the angle

In the parallelogram ABCD on the side BC, point E is marked so that AB = BE. Find the angle BCD if the angle EAD = 30 degrees.

Angle BEA = angle EAD = 30 ° (internal cross lying).
Consider a triangle ABE, it is isosceles (AB = BE according to the problem statement), which means that the angles at the base are equal: angle BEA = angle BAE = 30 °. Find the degree measure of the vertex of an isosceles triangle, that is, the angle ABE:
Angle ABE = 180 ° – (30 ° + 30 °) = 180 ° – 60 ° = 120 °
Find the corner BCD, it is adjacent (adjacent) to the angle ABE. The sum of adjacent (adjacent) angles in a parallelogram is 180 °.
angle BCD = 180 ° – angle ABE = 180 ° – 120 ° = 60 °
Answer: The BCD angle is 60 °. One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.