### Video Transcript

In the given rhombus π΄π΅πΆπ·, the measure of angle π΅πΆπ· equals 36 degrees. Find the measure of angle π΅π΄πΆ.

Letβs recall that a rhombus is a quadrilateral or four-sided shape that has all four sides equal in length. Weβre told that the angle π΅πΆπ· is 36 degrees. We need to find this smaller angle π΅π΄πΆ. In order to do this, weβll need to remember some of the properties of a rhombus.

One of the angle properties is that opposite angles are equal. Looking at the diagram, this would mean that angle π΅π΄π· would be equal to angle π΅πΆπ·. Theyβll both be 36 degrees. Of course, the angle that weβre looking for is angle π΅π΄πΆ. Now, while it might look as though itβs half of this angle, we need to be sure. We can in fact recall that the diagonals will bisect the angles, which means they cut them exactly in half. Line segment π΄πΆ is a diagonal of the rhombus.

We can note down what weβve discovered. Angle π΅π΄π· is equal to angle π΅πΆπ· because theyβre opposite angles. And weβve determined that both of those will then be 36 degrees. Angle π΅π΄πΆ will be half of angle π΅π΄π· because we have the diagonals bisecting the angles. To find the measure of angle π΅π΄πΆ, weβll half 36 degrees, giving us an answer of 18 degrees.