Using alternate interior angles to show two lines are parallel

The video tutorial explains how to determine if two lines, M and N, are parallel by using the concept of alternate interior angles. It describes the process of setting up equations to prove that the angles are equal and solving for the variable X. When X equals 63, the angles are equal, confirming that lines M and N are parallel.

What is the relationship between alternate interior angles and parallel lines?

• They are always equal.

• They are always supplementary.

• If they are equal, the lines are parallel.

• If they are supplementary, the lines are parallel.

What is the first step in proving that two angles are equal?

• Add the angles.

• Multiply the angles.

• Subtract the angles.

• Set the angles equal to each other.

What equation is set up to solve for X in the proof?

• 21 - X = 84

• X - 21 = 84

• X + 21 = 84

• 21 + X = 84

What is the value of X that makes the angles equal?

• 42

• 21

• 63

• 84

What conclusion can be drawn when the angles are equal?

• The lines are perpendicular.

• The lines are parallel.

• The lines are intersecting.

• The lines are skew.