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

An obtuse angle is one which is greater than a right angle.

What other obtuse angle has its vertex at p?

Obtuse means blunt.

Read three obtuse angles whose vertices are at x.

Acute and obtuse angles are also called oblique angles.

LESSON TENTH.

REVIEW.

Read all the right angles formed by the lines a b and c d. (Diagram [10].)

Why are the adjacent angles c e b, b e d, right angles?