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

By means of Fig. B prove,—

3. That the adjacent angles a c n, n c b, are equal to two right angles.

4. That the adjacent angles a c m, m c b, are equal to two right angles.

By means of Fig. C prove,—

5. That the adjacent angles a c m, m c b, are equal to two right angles.

6. That the adjacent angles a c n, n c b, are equal to two right angles.

By means of Fig. D prove,—

7. That the adjacent angles a c n, n c b, are equal to two right angles.

8. That the adjacent angles b c m, m c a, are equal to two right angles.