If two sides of a triangle are notcongruent, then the larger angle lies opposite the longer side.
∠ E, ∠ F, ∠ D
Practice makes perfect
We want to use the given side lengths of △ DEF to compare the angles of the same triangle.
DE=15, EF=18, DF=5
Before we attempt to order the angles of the triangle, let's draw it so that we can visualize the relationship between the sides and the angles.
We know that, if two sides of a triangle are notcongruent, then the larger angle lies opposite the longer side. Applying this rule to our triangle, we can write the angles in order from smallest to largest.
ccccc
5 & < & 15 & < & 18
DF & < & DE & < & EF
m∠ E& < & m∠ F & < & m∠ D
