Answer:
[tex]m\angle L = 100^{\circ}[/tex].
[tex]m\angle J = 80^{\circ}[/tex].
[tex]m\angle M = 100^{\circ}[/tex].
Step-by-step explanation:
Since segment [tex]JM[/tex] is parallel to segment [tex]KL[/tex], quadrilateral [tex]JKLM[/tex] is a trapezoid.
Segment [tex]JK[/tex] and segment [tex]LM[/tex] (the two legs of this trapezoid) are equal in length. Hence, trapezoid [tex]JKLM[/tex] would be an isoscele trapezoid. By symmetry, [tex]m\angle L = m \angle K = 100^{\circ}[/tex].
Line [tex]JK[/tex] traverses line [tex]JM[/tex] and line [tex]KL[/tex]. [tex]\angle J[/tex] and [tex]\angle K[/tex] are a pair of consecutive interior angles as they are both between [tex]JM\![/tex] and [tex]KL\![/tex] and are on the same side of the traversal, [tex]JK\![/tex].
Since line [tex]JM[/tex] is parallel to line [tex]KL[/tex], any pair of consecutive interior angles between these two lines would add up to [tex]180^{\circ}[/tex] (supplementary angles.) Thus, [tex]\angle J[/tex] and [tex]\angle K[/tex] are supplementary angles; [tex]m\angle J + m\angle K = 180^{\circ}[/tex].
Since [tex]m\angle K = 100^{\circ}[/tex], [tex]m\angle J = 180^{\circ} - m\angle K = 180^{\circ} - 100^{\circ} = 80^{\circ}[/tex].
