### As student many times, you are confronted with having to complete proofs, and you think: How do I start completing the proof? Or you just find difficult to understand the proofs that your teacher, or the textbook present to you.

### In this lesson, you will be given several examples that use colors and sequence to highlight each one of the steps in the corresponding proof; then you are shown the same proof with different labels to order the reasons. You will find it challenging while having some fun!

** Lesson's Content **

** Lesson's Glossary **

**Alternate exterior angles **

Exterior angles on alternate sides of the transversal (not on the same parallel line)

** Alternate interior angles **

Interior angles on alternate sides of the transversal (not on the same parallel line)

** Complementary angles **

Two positive angles that when added give 90 degrees.

**Corresponding angles **

Any pair of angles in similar locations with respect to a transversal.

**Linear pair **

2 supplementary adjacent angles whose non-common sides form a line.

**Parallel lines **

Two or more coplanar lines that never intersect.

**Perpendicular lines **

Two segments, rays, or lines that form a 90 degree angle.

**Postulate **

A statement assumed to be true without proof.

**Proof **

A sequence of justified conclusions used to prove the validity of an if-then statement.

**Supplementary angles **

Two positive angles whose measures add to 180 degrees.

**Theorem**

A theorem in mathematics is a proven fact. A theorem about polygon must be true for every polygon; there can be no exceptions. An idea which works in several different cases is not enough.

**Transversal **

A line that intersects others.

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