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

It is called a “radius.”—(Plural, radii.)

A radius is a straight line that joins the centre to a point of the circumference.

Read five radii.

Which is farther from the centre, the point a or the point d?

Can the radius c d be greater than the radius c a? Or greater than c v, or c o?

Then all radii of the same circle are equal to each other.

What do we call the lines o d, c d, c o?

What part of the diameter o d is the radius o c?

Name a chord that is produced without the circle.

It is called a “secant.”