Exam 3: Parallel Lines

For coplanar lines r, s, and t, if r ⊥ t and s ⊥ t, then r || s.

When two parallel lines are cut by a transversal, and are a pair of corresponding angles that are formed. If    and   , find x .

Find the sum of the interior angles for an octagon.

Of the upper case letters R, S, and T, which one has point symmetry?

Given line l, how many lines in space can be drawn parallel to l?

Assuming that statements (1)and (2)are true, which conclusion completes the Law of Negative Inference? (1)P Q (2)∼ Q

If two lines in space do not meet, they must be parallel.

The upper case H has point symmetry.

Write the first statement of the indirect proof for this statement:"If coplanar lines l and m are not perpendicular to the same line t, then l and m are not parallel."

For lines l, m, and n to be parallel by pairs, the three lines must be coplanar lines.

Given the coplanar lines and the fact that , which lines must be parallel?

When lines a and b are cut by transversal d , and are a pair of alternate exterior angles that are formed. If and , find x .

It is possible for a triangle to be both isosceles and obtuse.

As shown, must be an isosceles triangle.

Through a point not on a given line, there is exactly one line parallel to the given line.

In ,   , , and . find .

If a triangle has exactly two congruent sides, then it is an isosceles triangle.

In , is a right angle. If m is 26 ° larger than m , find m .

The number of diagonals D for a polygon of n sides is given by . Find the number of sides for a polygon that has 14 diagonals.

Suppose that . Which must be true?