What led to the split of the mongol empire

The empire began to split due to wars over succession, as the grandchildren of Genghis Khan disputed whether the royal line should follow from his son and initial heir Ögedei or from one of his other sons, such as Tolui, Chagatai, or Jochi.

In the diagram, which pair of angles are vertical angles?

A transversal intersects 2 lines to form 8 angles. Clockwise from the top, the angles are 1, 2, 3, 4; 5, 6, 7, 8.

Angle 1 and Angle 2

Angle 4 and Angle 6

Angle 6 and Angle 8

Angle 5 and Angle 3