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. C,—

5. Prove that the adjacent angles Red, Blue, are equal to two right angles.

6. Prove that the adjacent angles Green, Yellow, are equal to two right angles.

7. Give the preceding demonstrations again, but name the angles by their letters instead of by their colors.

Diagram 32.

TEST LESSON.

By means of Fig. A prove,—

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

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