÷ÈÓ°Ö±²¥

State the postulate or theorem that justifies each statement.

$∠3â‰\dots ∠6$

Complete each statement with the words always, sometimes or never.

If a triangle is scalene then it is isosceles.

Complete each statement with the word always, sometimes, or never.

If two lines are cut by a transversal and same-side interior angles are complementary, then the lines are $\underset{¯}{?}$ parallel.

Complete each statement with the word always, sometimes, or never.

When there is a transversal of two lines, the three lines are coplanar

Find the sum of the measures of angles formed at the tips of each star.

a. Five-pointed star

b. Six-pointed star

c. Using inductive reasoning, suggest a formula for the sides of the angle measures at the tips of an n-printed star.

d. Using deductive reasoning, justify your formula.

Complete each statement with the word always, sometimes, or never.

Three lines intersecting in one point are coplanar

Complete each statement with the word always, sometimes, or never.

Two lines that are not coplanar intersect.

Given: $\overline{PR}$bisects $∠SPQ$and $\overline{PS}âŠ\yen \overline{SQ};\overline{RQ}âŠ\yen \overline{PQ}$.

Which numbered angles must be congruent?

1. Draw two parallel lines and a transversal.
2. Use a protractor to draw bisectors of two same-side interior angles.
3. Measure the angles formed by the bisectors. What do you notice?
4. Prove your answer to part (c).

A pair of same-side interior angles are trisected (divided into three congruent angles) by the red lines in the diagram. Find out what you can about the angles of ABCD.