Solution
Notice that angle 1 and angle 8 are alternate interior angles
Hence,
[tex]\angle1=\angle8[/tex]
Notice that angle 8 and angle 7 are supplementary angle
Since angle 1 is equal to angle 8 it follows
Angle 1 and angle 7 are supplementary
Angle 1 and angle 3 are vertically opposite angle
Hence
[tex]\angle1=\angle3[/tex]
This implies that
