Last visit was: 21 Nov 2024, 11:51 It is currently 21 Nov 2024, 11:51

Close

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

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 GRE 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.

Close

Request Expert Reply

Confirm Cancel
User avatar
Retired Moderator
Joined: 07 Jun 2014
Posts: 4812
Own Kudos [?]: 11188 [3]
Given Kudos: 0
GRE 1: Q167 V156
WE:Business Development (Energy and Utilities)
Send PM
avatar
Intern
Intern
Joined: 07 Jan 2017
Posts: 11
Own Kudos [?]: 10 [1]
Given Kudos: 0
Send PM
Verbal Expert
Joined: 18 Apr 2015
Posts: 30001
Own Kudos [?]: 36335 [0]
Given Kudos: 25926
Send PM
User avatar
Retired Moderator
Joined: 07 Jun 2014
Posts: 4812
Own Kudos [?]: 11188 [0]
Given Kudos: 0
GRE 1: Q167 V156
WE:Business Development (Energy and Utilities)
Send PM
Re: In the figure below, equilateral triangle ABC is inscribed i [#permalink]
1
Expert Reply
Hi darkdevil8z,

Yes you are quite correct.

If you dont know this property you might even solve it with trigonometry.

Join Ao; and AO=BO=OE= 4 and triangle AOD is a right triangle with AO bisecting the angle CAB of triangle ABC.

So OD = \(AO \times sine(\frac{60}{2})\) = \(AO \times sine(30)\) =\(AO\times\frac{1}{2}\) =2

DE = OE-OD = 4 -2=2.

Regards,
avatar
Intern
Intern
Joined: 07 Jan 2017
Posts: 11
Own Kudos [?]: 10 [0]
Given Kudos: 0
Send PM
Re: In the figure below, equilateral triangle ABC is inscribed i [#permalink]
1
Carcass wrote:
Hi,

please format the question properly. Screencast of a question instead of the text are avoidable. Moreover, follow the rules for posting on the board and chose the right sub-forum to post the questions.

Thank you a lot for your collaboration. ASAP our expert sandy will reply to your question.

Regards

Hi Carcass, sorry for didn't post properly, as a new user (less than 5 posts), I'm not able to post the urI... (because it restrict new user to post a urI, if he/she less than 5 posts) as for the sub-forum, sorry for that, I didn't know the sub-forum exist.

As for Sandy, thanks for reply. =)
Verbal Expert
Joined: 18 Apr 2015
Posts: 30001
Own Kudos [?]: 36335 [0]
Given Kudos: 25926
Send PM
Re: In the figure below, equilateral triangle ABC is inscribed i [#permalink]
Expert Reply
darkdevil8z wrote:
Carcass wrote:
Hi,

please format the question properly. Screencast of a question instead of the text are avoidable. Moreover, follow the rules for posting on the board and chose the right sub-forum to post the questions.

Thank you a lot for your collaboration. ASAP our expert sandy will reply to your question.

Regards

Hi Carcass, sorry for didn't post properly, as a new user (less than 5 posts), I'm not able to post the urI... (because it restrict new user to post a urI, if he/she less than 5 posts) as for the sub-forum, sorry for that, I didn't know the sub-forum exist.

As for Sandy, thanks for reply. =)


No sorry Sir. Just point out :)

A board clean is a board efficient
avatar
Intern
Intern
Joined: 07 Jan 2017
Posts: 11
Own Kudos [?]: 10 [0]
Given Kudos: 0
Send PM
Re: In the figure below, equilateral triangle ABC is inscribed i [#permalink]
1
After this message, I think I no longer have urI restrict problem, and ill post the sub-forum as you mentioned, thanks for point out. =)
avatar
Intern
Intern
Joined: 08 Apr 2018
Posts: 44
Own Kudos [?]: 20 [0]
Given Kudos: 0
Send PM
Re: GRE Math Challenge #23 equilateral triangle ABC is inscribed [#permalink]
sandy wrote:
Attachment:
figure 14.jpg



In figure below, equilateral triangle ABC is inscribed in circle O, whose radius is 4. Altitude BD is extended until it intersects the circle at E. What is the length of DE?




A. 1
B. \(\sqrt{3}\)
C. 2
D. 2 \(\sqrt{3}\)
E. 4 \(\sqrt{3}\)

Please solution for this?
avatar
Intern
Intern
Joined: 25 May 2018
Posts: 7
Own Kudos [?]: 2 [0]
Given Kudos: 0
Send PM
Re: GRE Math Challenge #23 equilateral triangle ABC is inscribed [#permalink]
2
Emike56 wrote:
sandy wrote:
Attachment:
figure 14.jpg



In figure below, equilateral triangle ABC is inscribed in circle O, whose radius is 4. Altitude BD is extended until it intersects the circle at E. What is the length of DE?




A. 1
B. \(\sqrt{3}\)
C. 2
D. 2 \(\sqrt{3}\)
E. 4 \(\sqrt{3}\)

Please solution for this?


@Emike56,

Join the line AO. Now, we have triangle AOD, which is a 30:60:90 triangle (<DAO = 30, <AOD = 60, <ADO =90). Hence, sides will be in the ratio of \(1:\sqrt{3}:2\).

We know AO = 4 (Radius of the circle).Hence, OD = 2 and AD = \(2\sqrt{3}\).

DE = OE - OD = 4 - 2 = 2. Answer(C).

Hope it helps.
avatar
Intern
Intern
Joined: 08 Apr 2018
Posts: 44
Own Kudos [?]: 20 [0]
Given Kudos: 0
Send PM
Re: GRE Math Challenge #23 equilateral triangle ABC is inscribed [#permalink]
1
ganand wrote:
Emike56 wrote:
sandy wrote:
Attachment:
figure 14.jpg



In figure below, equilateral triangle ABC is inscribed in circle O, whose radius is 4. Altitude BD is extended until it intersects the circle at E. What is the length of DE?




A. 1
B. \(\sqrt{3}\)
C. 2
D. 2 \(\sqrt{3}\)
E. 4 \(\sqrt{3}\)

Please solution for this?


@Emike56,

Join the line AO. Now, we have triangle AOD, which is a 30:60:90 triangle (<DAO = 30, <AOD = 60, <ADO =90). Hence, sides will be in the ratio of \(1:\sqrt{3}:2\).

We know AO = 4 (Radius of the circle).Hence, OD = 2 and AD = \(2\sqrt{3}\).

DE = OE - OD = 4 - 2 = 2. Answer(C).

Hope it helps.

Thanks. I am assuming that we have made O the centre of the circle. This was not stated in the question nor in your solution.
avatar
Intern
Intern
Joined: 25 May 2018
Posts: 7
Own Kudos [?]: 2 [0]
Given Kudos: 0
Send PM
Re: GRE Math Challenge #23 equilateral triangle ABC is inscribed [#permalink]
Emike56 wrote:

In figure below, equilateral triangle ABC is inscribed in circle O, whose radius is 4. Altitude BD is extended until it intersects the circle at E. What is the length of DE?




A. 1
B. \(\sqrt{3}\)
C. 2
D. 2 \(\sqrt{3}\)
E. 4 \(\sqrt{3}\)
Please solution for this?

Thanks. I am assuming that we have made O the centre of the circle. This was not stated in the question nor in your solution.


@Emike56,
Thank you for the query.
Let me explain.

When we say triangle ABC this implies that A, B, and C are the three vertices of the triangle.

Similarly, the question says "Circle O", which implies that O is the center of the circle.

I hope this helps.
User avatar
GRE Prep Club Legend
GRE Prep Club Legend
Joined: 07 Jan 2021
Posts: 5030
Own Kudos [?]: 74 [0]
Given Kudos: 0
Send PM
Re: GRE Math Challenge #23 equilateral triangle ABC is inscribed [#permalink]
Hello from the GRE Prep Club BumpBot!

Thanks to another GRE Prep 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.
Prep Club for GRE Bot
Re: GRE Math Challenge #23 equilateral triangle ABC is inscribed [#permalink]
Moderators:
GRE Instructor
83 posts
GRE Forum Moderator
37 posts
Moderator
1111 posts
GRE Instructor
234 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne