Examine the triangle at right. Each part is a separate problem.

1. If $m∠D = 48º$ and $m∠F = 117º$, then what is $m∠E$?

   Step (a):

   Use the Triangle Angle Sum Theorem: $48º + 117º + m∠E = 180º$

2. Solve for $x$ if $m∠D = 4x + 2º$, $m∠F = 7x – 8º$, and $m∠E = 4x + 6º$. Then calculate $m∠D$.

   Hint (b):

   Use the same method as part (a).

3. If $m∠D = m∠F = m∠E$, what type of triangle is $ΔFED$?

   Hint (c):

   If all of the angles have equal measure, then all of the sides have equal measure.