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

LESSON FIFTH.

ANGLES.

Do the lines a b and c d (Diagram [5].) point in the same direction? (See note, page [15].)

Then they form an angle with each other.

What other line forms an angle with a b?

Which of the two lines c d, e f, has the greater difference of direction from the line a b?

Then which one forms the greater angle with a b?

What line forms a still greater angle with the line a b?

An angle is the difference of direction of two straight lines.

If the lines a b, e f, were made longer, would their direction be changed?