Chapter 4 - Lines & Angles

Question 1

How many degrees does a line measure?

Answer 1

180 degrees

Question 2

What are perpendicular lines?

Answer 2

lines that intersect at 90 degree angle.

Question 3

What are the two major line-angle relationships that you must know for GMAT?

Answer 3

1) The angles formed by any intersecting lines
2) The angles formed by parallel lines cut by a transversal

Question 4

What are the three imp properties of intersecting lines?

Answer 4

1) Interior angles formed by intersecting lines form a circle so the sum of these angles is 360 degrees.
2) Interior angles that combine to form a line sum to 180 degrees and are called SUPPLEMENTARY angles.
3) Angles found opposite each other where the two lines intersect are equal and are called VERTICAL angles

Question 5

What is a Exterior angle of a triangle?

Answer 5

An EXTERIOR ANGLE of a triangle is equal in measure to the sum of the two opposite INTERIOR ANGLES.

This property is frequently tested on GMAT. Often you have to redraw the triangle to isolate the exterior angle you need.

Question 6

What are parallel lines cut by a Transversal

Answer 6

** GMAT frequently uses diagrams with parallel lines cut by transversal.

In a diagram where parallel lines are cut by a transversal, all ACUTE angles (less than 90 degrees) are equal and all OBTUSE angles (more than 90 but less than 180) are equal. Any Acute angle is supplementary to any obtuse angle.