Video Transcript
Find the value of 𝑥 in the
figure.
We can start this question by
identifying some key information we are given. Firstly, by the markings on the
lines, we observe that we have two parallel lines. This third line can be considered
as a transversal of these parallel lines. As we need to find the unknown
angle measure of 𝑥 degrees, let’s recall some angle facts about the angles created
between two parallel lines and a transversal.
We’re very used to seeing the
angles in parallel lines drawn in nice horizontal lines like this. The congruent angles, which include
corresponding, alternate interior, and alternate exterior angles, can be represented
as shown. So, sometimes, when the parallel
lines aren’t horizontal or even vertical, it may be difficult to work out any
congruent or supplementary angle measures.
But if we consider the angles of
measure 𝑥 degrees and 124 degrees, these are a pair of alternate exterior
angles. And therefore, they will be equal
in measure. We can give the answer that 𝑥 is
124. Note that we don’t need to include
the degree symbol, as the unknown angle was defined as 𝑥 degrees, which would be
124 degrees.
