Video Transcript
From the information in the figure
below, find the measure of angle π΄πΈπΆ.
Angle π΄πΈπΆ is shown in the
diagram. This can be split into the sum of
two other angles, angle π΄πΈπΉ and angle πΆπΈπΉ. We can use our angle properties
involving parallel lines to calculate these two values. The lines π΄π΅, πΈπΉ, and πΆπ· are
parallel as indicated on the diagram. We know that alternate angles are
congruent. These are sometimes referred to as
βzeeβ or βzedβ angles. This means that angle π΅π΄πΈ is
equal to angle π΄πΈπΉ. Theyβre both equal to 92
degrees.
Cointerior or supplementary angles
sum to 180 degrees. These are often known as C
angles. In this question, angle πΆπΈπΉ plus
131 degrees is equal to 180 degrees. This means that our missing angle
π¦, angle πΆπΈπΉ, is equal to 49 degrees. We can therefore calculate the
measure of angle π΄πΈπΆ by adding 92 degrees and 49 degrees. This is equal to 141 degrees.