GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Which is greater a+b-c or zero
[#permalink]
28 Dec 2018, 11:18
28 Dec 2018, 11:18
Expert Reply
00:00
Question Stats:
80% (00:25) correct
19% (00:53) wrong based on 126 sessions
Hide Show timer Statistics
Attachment:
#GREpracticequestion Which is greater a+b-c or zero.jpg [ 7.45 KiB | Viewed 5640 times ]
Quantity A |
Quantity B |
a+b-c |
0 |
A) Quantity A is greater.
B) Quantity B is greater.
C) The two quantities are equal.
D) The relationship cannot be determined from the information given.
Intern
Joined: 21 Nov 2018
Posts: 24
Given Kudos: 0
GRE 1: Q170 V170
Re: Which is greater a+b-c or zero
[#permalink]
28 Dec 2018, 18:58
28 Dec 2018, 18:58
1
In the case of a triangle with one of the sides extended we have what is called an external supplementary angle (in this problem this angle is C degrees). It is "External" because it is not one of the three angles that makes up the triangle. "Supplementary" because it sits on a straight line and together with the adjacent interior angle it adds to 180.
Let's call the final angle inside the triangle D degrees. So inside the triangle we have angles of measures A degrees B degrees and D degrees. The external supplementary angle is C degrees. From here on I will just call them angles A B D and C.
With the supplementary angle rule we know that any two angles that make a straight line are equal to 180 degrees. So C + D = 180.
But it is also true that the angles that make up a triangle equal 180 degrees. So A + B + D = 180.
Since they each equal 180 we can set these equations equal to each other so that A + B + D = C + D. Subtract D from each side and you have A + B = C
The rule that takes you directly to "A + B = C" is as follows, "The measure of an external supplementary angle is equal to the sum of the two internal non-adjacent angles."
Clearly if A + B = C then quantity A equals zero.
Let's call the final angle inside the triangle D degrees. So inside the triangle we have angles of measures A degrees B degrees and D degrees. The external supplementary angle is C degrees. From here on I will just call them angles A B D and C.
With the supplementary angle rule we know that any two angles that make a straight line are equal to 180 degrees. So C + D = 180.
But it is also true that the angles that make up a triangle equal 180 degrees. So A + B + D = 180.
Since they each equal 180 we can set these equations equal to each other so that A + B + D = C + D. Subtract D from each side and you have A + B = C
The rule that takes you directly to "A + B = C" is as follows, "The measure of an external supplementary angle is equal to the sum of the two internal non-adjacent angles."
Clearly if A + B = C then quantity A equals zero.
