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

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 350,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Re: IN TRIANGLE ABC [#permalink]
21 Dec 2010, 07:31

10

This post received KUDOS

Expert's post

5

This post was BOOKMARKED

Attachment:

trig2uc8.png [ 9.64 KiB | Viewed 23385 times ]

In triangle ABC above, what is the length of side BC?

As <BDC=<BCD then the BD=BC. Also as <ADB=180-2x (exterior angle) and the sum of the angles of a triangle is 180 degrees then in triangle ADB we'll have: x+(180-2x)+<ABD=180 --> <ABD=x. Now, we have that <ABD=x=<DAB so AD=BD --> AD=BD=BC.

Question: BC=?

(1) Line segment AD has length 6 --> AD=BD=BC=6. Sufficient. (2) x = 36 --> we know only angles which is insufficient to get the length of any line segment.

Re: IN TRIANGLE ABC [#permalink]
26 Feb 2011, 23:52

1

This post received KUDOS

Expert's post

vibhav wrote:

the one point that puzzles me is how did you get /BAD = x ?

It's given that <BAD=x degrees (refer to the diagram in my first post on the page). Some OG books have a typo missing this info (as in vibhav post). _________________

The question asks the length of side BC. From the figure, you can see that triangle BDC is an isosceles triangle with BD = BC. Thus, to know the length of BC, it is okay if we know the length of BD.

Statement 1: To solve such problems, you have to know that in a triangle, the measure of the exterior angle is equal to the sum of the two non-adjacent angles of the triangle.

That is, in the given figure, for triangle ABD, angle BDC is the exterior angle. Thus, BDC = ABD + BAD That is, 2x = ABD + x. Thus ABD = x.

Now, you can see that triangle ABD is an isosceles triangle in which AD = BD = 6. Thus, BD = BC = 6. SUFFICIENT

Statement 2: x = 36 does not tell you anything about the length of any side. INSUFFICIENT

Re: Triangle Problem [#permalink]
20 Mar 2012, 18:09

Using Similar triangles we know that 1) BD = BC (angle BDC = angle BCD) 2) We know angle BDA = 180-2x which means angle ABD = x 3) So, from the second similar triangle we know that angle BAD = angle ABD = x 4) Using similar triangles again; AD = BD 5) Combing 1 and 4; AD = BD = BC.

Re: In triangle ABC above, what is the length of side BC? [#permalink]
23 Apr 2014, 21:48

Expert's post

jlgdr wrote:

Why is AD=BD=BC? If AD is opposite to X, BD opposite to X as well and BC opposite to 2x? Shouldn't BC be larger than both or equal to both TOGETHER?

Thanks for clarifying

Cheers! J

Yes but they are sides of different triangles. Note that by the same logic, BD is opposite to 2x as well. The point is that it is opposite to x in one triangle (ABD) and opposite to 2x in another triangle (BDC).

BC will be equal to BD because they are both opposite 2x in triangle BDC.

AD will be equal to BD because they are both opposite angle x in triangle ABD.

Re: In triangle ABC above, what is the length of side BC? [#permalink]
20 Jun 2014, 02:35

Bunuel wrote:

Attachment:

trig2uc8.png

In triangle ABC above, what is the length of side BC?

As <BDC=<BCD then the BD=BC. Also as <ADB=180-2x (exterior angle) and the sum of the angles of a triangle is 180 degrees then in triangle ADB we'll have: x+(180-2x)+<ABD=180 --> <ABD=x. Now, we have that <ABD=x=<DAB so AD=BD --> AD=BD=BC.

Question: BC=?

(1) Line segment AD has length 6 --> AD=BD=BC=6. Sufficient. (2) x = 36 --> we know only angles which is insufficient to get the length of any line segment.

Answer: A.

Thanks for the answer... I guess I need to expand my thought process... _________________

I'm happy to help if you wanna know about Ross & UMich, but please do not come to me with your GMAT issues or questions. And please add a bit of humor to your questions or you'll bore me to death.

Re: In triangle ABC above, what is the length of side BC? [#permalink]
08 Sep 2015, 18:20

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________

In triangle ABC above, what is the length of side BC? [#permalink]
30 Sep 2015, 12:10

blendercroix wrote:

I'm sorry guys but the answer does not make sense at all!!

<BDC = <BCD ( I got this) <ADB = 180 - 2x (I got this) The sum of this triangle is 180

180 = x + (180-2x) + <ABD

now I'm confused. How did you come up with <ABD is equal to x??????? Even if we substitute <ABD with x, thus would be:

180 = x + 180-2x + x 180 = 2x -2x +180 180 = 180

The sum of two non-adjacent interior angles of a triangle is always equal to the measure of an exterior angle of a triangle. Even if you didn't know this property, say <ABD is y, so now we have <BAD is x, <ABD is y and <BDA is 180-2x. The sum of the interior angles of a triangle must sum to 180 degrees. So we have x+y+180-2x=180-->y=x

gmatclubot

In triangle ABC above, what is the length of side BC?
[#permalink]
30 Sep 2015, 12:10

On September 6, 2015, I started my MBA journey at London Business School. I took some pictures on my way from the airport to school, and uploaded them on...

When I was growing up, I read a story about a piccolo player. A master orchestra conductor came to town and he decided to practice with the largest orchestra...

I’ll start off with a quote from another blog post I’ve written : “not all great communicators are great leaders, but all great leaders are great communicators.” Being...