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

5. Prove the same, using the angle m n d.

By means of Fig. B,—

6. Prove that the exterior alternate angles c m e, f n b, are equal, using the angle n m d.

7. Prove the same, using the angle a n m.

8. Prove the exterior alternate angles e m d, a n f, equal, using the angle c m n.

9. Prove the same, using the angle m n b.

Diagram 43.

PROPOSITION VI. THEOREM.

DEVELOPMENT LESSON.