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.

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:

Attend a Veritas Prep GMAT Class for Free. With free trial classes you can work with a 99th percentile expert free of charge. Learn valuable strategies and find your new favorite instructor; click for a list of upcoming dates and teachers.

Join us for a debate on how these elite MBA programs are different from each other, what are their strengths & weaknesses, and how to decide which one is better for you.

Join us for a debate between the two MBA experts on how these elite MBA programs are different from each other, what are their strengths & weaknesses, and how to decide which one is better for you.

Only 2000 test-takers score 760 or higher annually. These students not only secure admissions at top B-schools, but they also get an estimated $100M in scholarships. Find out more...

In the figure shown, AC = 2 and BD = DC = 1. What is the measure of
[#permalink]

Show Tags

Updated on: 16 Apr 2018, 11:40

10

Top Contributor

2

AbdurRakib wrote:

Attachment:

2018.OG.05.026.q.png

In the figure shown, AC = 2 and BD = DC = 1. What is the measure of angle ABD?

A. 15° B. 20° C. 30° D. 40° E. 45°

If AC = 2 and DC = 1, then we can conclude that AD = 1 Add this information to the diagram...

If AD = 1 and BD = 1, then ∆ABD is an ISOSCELES triangle, which means ∠DAB = ∠ABD are EQUAL...

If we let x = BOTH ∠DAB and ∠ABD, then we can use the fact that angles in a triangle add to 180º We can write: x + x + 120 = 180 Simplify: 2x + 120 = 180 Solve: x = 30

Re: In the figure shown, AC = 2 and BD = DC = 1. What is the measure of
[#permalink]

Show Tags

04 Jul 2017, 01:55

Angle BDC is 60 degree(because the angle in a straight line is equal to 180 degree) Since BD = DC(as given in the question stem) the triangle must be equilateral. Therefere DC=1.

Since AC=2, AD = AC - DC = 1 Angle ABD = Angle DAB = x(Angles opposite equal sides are equal)

We know that the sum of angles in a triangle is 180 degree, 2x + 120 = 180 Angle ABD(x) = 30 degree(Option C) _________________

You've got what it takes, but it will take everything you've got

Re: In the figure shown, AC = 2 and BD = DC = 1. What is the measure of
[#permalink]

Show Tags

15 Nov 2017, 15:46

AbdurRakib wrote:

Attachment:

2018.OG.05.026.q.png

In the figure shown, AC = 2 and BD = DC = 1. What is the measure of angle ABD?

A. 15° B. 20° C. 30° D. 40° E. 45°

Since AC = 2 and DC = 1, AD must be 1. Since BD = 1, this makes triangle ABD an isosceles triangle with angle D as the vertex angle and angles A and ABD as the base angles. We know that angles A and ABD are equal because the sides opposite them are equal. If we let each of the base angles = x, we can create the following equation:

In the figure shown, AC = 2 and BD = DC = 1. What is the measure of
[#permalink]

Show Tags

27 Sep 2019, 07:16

Can someone help me, I have a flaw in my logic. I totally understand it, but I would have solved it from the second triangle.

Is it true that angles in the triangle on the right are 60 degree?

I somehow got stuck because I thought that if those angles are 60, the upper angle (aka the one we are looking for) has to be 120. Is this wrong because it would only be 120 if I would draw a line from up there and the touch on the line would make it 180?

Re: In the figure shown, AC = 2 and BD = DC = 1. What is the measure of
[#permalink]

Show Tags

18 Jun 2020, 23:24

chrtpmdr wrote:

Can someone help me, I have a flaw in my logic. I totally understand it, but I would have solved it from the second triangle.

Is it true that angles in the triangle on the right are 60 degree?

I somehow got stuck because I thought that if those angles are 60, the upper angle (aka the one we are looking for) has to be 120. Is this wrong because it would only be 120 if I would draw a line from up there and the touch on the line would make it 180?

See drawing:

Are you saying angle ABC is 120 as well? That's where the error is. You can solve this many ways: the easy way is to realize that angle BDC is 60(linear pair). AC= 2 (given).If DC=1, then AD= 1 (AD+DB=AC). That means triangle ADB is an isosceles triangle with base angles DAB and DBA congruent. angle DAB + angle DBA+120=180. From there you get angle DBA is equal to 30 degrees.

Now if you wanted to use the triangle on the right, you have correctly deduced that the triangle on the right is equiangular. Note that segment BD is the median of triangle ABC. Since AD=BD=DC, we know that the triangle ABC is a right triangle. (the median on the hypotenuse of a right triangle divides the triangle into two isosceles triangles. That means ABC is a right angle. Since DBC is 60 degrees, then ABD is 30 degrees.

gmatclubot

Re: In the figure shown, AC = 2 and BD = DC = 1. What is the measure of
[#permalink]
18 Jun 2020, 23:24