Marks' first lessons in geometry / In two parts. Objectively presented, and designed for the use of primary classes in grammar schools, academies, etc.

by Bernhard Marks

Are they interior or exterior angles?

Then they are “opposite interior angles.”

Why are they opposite? Why interior?

Read the opposite exterior angles on the left of the line e f.

Read the opposite interior angles on the same side.

Are the opposite angles e m a, m n c, both exterior or interior?

Then they are opposite exterior and interior angles.

Read two pairs of opposite exterior and interior angles on the right of e f. On the left.

ALTERNATE ANGLES.

Do the angles b m n, m n c, lie on the same side of the intersecting line e f?