LESSON SEVENTH.
RELATIONS OF ANGLES.
ADJACENT ANGLES.
Are the angles a e c, c e b (Diagram [7].), on the same side of any line? What line?
By what other straight line are they both formed?
Then, because they are both on the same side of the same straight line a b, and are both formed by the second straight line c d, they are called “adjacent angles.”
The angles c e b, b e d are both on the same side of what straight line?
They are both formed by what second straight line?
Then what kind of angles are they?
Why are they called adjacent angles?
Read the adjacent angles below the line a b. Below the line c d.
How many pairs of adjacent angles can be formed by two straight lines?
Read all the adjacent angles formed by the lines l m and n p.
VERTICAL ANGLES.
Are the angles a e c, b e d formed by the same straight lines?
Are they adjacent angles?
They are called “vertical angles.”
Vertical angles are angles formed by the same straight lines, but not adjacent to each other.
Read the other pair of vertical angles formed by the lines a b, c d.
Read all the vertical angles formed by the lines f g, i h. By l m, n p.
Why are the angles l o n, n o m adjacent angles?
Why are the angles l o n, p o m vertical angles?
Diagram 8.