McGraw-Hill Education GRE 2019

Note that if a figure says “Not Drawn to Scale,” then the relationships

between the sides and angles in the diagram do not match their visual

appearance. However, the opposite is also true: if the figure does not say

“Not Drawn to Scale,” then you can assume that the diagram is accurate.

Nonetheless, you must be careful about making assumptions.

Lines and Angles

An angle is formed at the intersection of two rays or lines. The measurement of an

angle can be between 0 degrees and 360 degrees. The angle below has a measure of

45 degrees.

45°

One type of angle that occurs throughout geometry questions is a right angle.

A right angle has a measure of 90 degrees and is denoted by the square at the

intersection of the two lines or rays. When two lines intersect to form a right angle,

those lines are said to be perpendicular.

A straight line will always have an angle measure of 180 degrees. From this,

you can infer Property 1: the angles on a line must add up to 180. Angles whose

measures sum to 180 are termed supplementary angles.

CD

b° b°

a° a°

What is the value of (a + b) in the figure above?

SOLUTION: Since these four angles lie on line CD:

a + a + b + b = 180

2 a + 2b = 180

a + b = 90

366 PART 4 ■ MATH REVIEW

04-GRE-Test-2018_313-462.indd 366 12/05/17 12:04 pm