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 500,000 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:

To find the angle between two lines, we need to know the slope of both lines. But as shown in the figure, this angle "a" can be either "x" or "y". But since we are given that a<90, we can find out which angle is required because x + y = 180. The slope of the second line is obviously 1. So the question is basically asking for the value of m.

1) Sufficient

2) We get y = bx + b. b is still unknown. Insufficient.

Answer is hence A.

Kudos Please... If my post helped.

Attachments

untitled.JPG [ 3.39 KiB | Viewed 4350 times ]

_________________

Did you find this post helpful?... Please let me know through the Kudos button.

We can find the angle of intersection b/w any 2 lines if we knw the values of their individual slopes.

For y = x + bm, slope is 1; for y = mx + b, slope is "m" (1) Tan (a) = (m - 1)/(1 + 1*m); tan(a) < 90 if its value is +ve;since m-1>0, no need to add/subtract from 180. Since statement 2 gives m=2, it is sufficient. (2) Test y=x+1, y=2x+2 and y=3x+3 with "y=x - 1, y=x-4, and y=x-9" y=x+1 and y=x gives 0 degrees y=2x+2 and y=x-4 gives a diffrent value...INSUFF _________________

KUDOS me if you feel my contribution has helped you.

Re: If lines y=mx+b and x=y+bm intersect at a degrees angle [#permalink]

Show Tags

20 Feb 2013, 16:07

m is the slope of the line y=mx+b

If you draw an equation for this line, you will find m to be the slope of the line and b to be the intersect on y axis(when x=0). This is called the slope-intercept form of line equation and you memorizing it will help you deal with such questions. The form of such lines is y=(slope)x+y-intersect

The other line x=y+bm can be written in a similar fashion

y=x-bm.

Going by the above stated formula, since the coefficient of x=1, slope =1. The y-intersect of the line is bm.

Hope that clarifies your doubt.

Sachin9 wrote:

Marcab wrote:

m= tan x. So x= tan inverse(m).

but m is slope of which line out of the that intersect?

Re: If lines y=mx+b and x=y+bm intersect at a degrees angle [#permalink]

Show Tags

01 Aug 2013, 00:34

abhisingla wrote:

Angle between 2 lines is m1-m2/1+m1m2 ..

We already know slope of line X = Y + bm.

Option A tells slope of line A - so suffcient but option B tells nothing so not sufficient

How do we apply this formula? In this question m1= 2 and m2=1, does that mean angle is \(\frac{2-1}{1+2.1} = \frac{1}{3}\) is there a \(tan^{-1}\)before this, so angle between two lines having slopes m1 and m2 \(= tan^{-1}\frac{m1-m2}{1+m1m2}\)

In short how do we actually determine the angle between 2 lines given their slopes? Thanks _________________

Re: If lines y=mx+b and x=y+bm intersect at a degrees angle [#permalink]

Show Tags

01 Aug 2013, 00:48

3

This post received KUDOS

2

This post was BOOKMARKED

stne wrote:

abhisingla wrote:

How do we apply this formula? In this question m1= 2 and m2=1, does that mean angle is \(\frac{2-1}{1+2.1} = \frac{1}{3}\) is there a \(tan^{-1}\)before this, so angle between two lines having slopes m1 and m2 \(= tan^{-1}\frac{m1-m2}{1+m1m2}\)

In short how do we actually determine the angle between 2 lines given their slopes? Thanks

We do not care about the actual measure of the angle.

When we have to determine the angle at which two lines intercept, the ONLY thing we have to know is the slope of each line . With statement 1 we get (note that I consider only the slopes of the two equations): line1: \(y=2x\) line2: \(y=x\)

Once we have those, we are able to determine the length of the angles at the point of intersection. Those angles are fixed and do not change, hence we can determine their length, but in this DS we do not care about the actual number. With statement 1, can you answer the question? YES, that's enough.

To determine the angle we would have to use formulas that are beyond the scope of the GMAT ("tan" for example) http://planetmath.org/anglebetweentwolines but the point here, as I said above, is not to find the measure. _________________

It is beyond a doubt that all our knowledge that begins with experience.

Re: If lines y=mx+b and x=y+bm intersect at a degrees angle [#permalink]

Show Tags

01 Aug 2013, 01:04

Zarrolou wrote:

stne wrote:

abhisingla wrote:

How do we apply this formula? In this question m1= 2 and m2=1, does that mean angle is \(\frac{2-1}{1+2.1} = \frac{1}{3}\) is there a \(tan^{-1}\)before this, so angle between two lines having slopes m1 and m2 \(= tan^{-1}\frac{m1-m2}{1+m1m2}\)

In short how do we actually determine the angle between 2 lines given their slopes? Thanks

We do not care about the actual measure of the angle.

When we have to determine the angle at which two lines intercept, the ONLY thing we have to know is the slope of each line . With statement 1 we get (note that I consider only the slopes of the two equations): line1: \(y=2x\) line2: \(y=x\)

Once we have those, we are able to determine the length of the angles at the point of intersection. Those angles are fixed and do not change, hence we can determine their length, but in this DS we do not care about the actual number. With statement 1, can you answer the question? YES, that's enough.

To determine the angle we would have to use formulas that are beyond the scope of the GMAT ("tan" for example) http://planetmath.org/anglebetweentwolines but the point here, as I said above, is not to find the measure.

That definitely helps ! Other solutions involving tan kept me wondering if indeed it was beyond scope or not,+1 _________________

Re: If lines y=mx+b and x=y+bm intersect at a degrees angle [#permalink]

Show Tags

18 Jun 2014, 07:19

Zarrolou wrote:

stne wrote:

abhisingla wrote:

How do we apply this formula? In this question m1= 2 and m2=1, does that mean angle is \(\frac{2-1}{1+2.1} = \frac{1}{3}\) is there a \(tan^{-1}\)before this, so angle between two lines having slopes m1 and m2 \(= tan^{-1}\frac{m1-m2}{1+m1m2}\)

In short how do we actually determine the angle between 2 lines given their slopes? Thanks

We do not care about the actual measure of the angle.

When we have to determine the angle at which two lines intercept, the ONLY thing we have to know is the slope of each line . With statement 1 we get (note that I consider only the slopes of the two equations): line1: \(y=2x\) line2: \(y=x\)

Once we have those, we are able to determine the length of the angles at the point of intersection. Those angles are fixed and do not change, hence we can determine their length, but in this DS we do not care about the actual number. With statement 1, can you answer the question? YES, that's enough.

To determine the angle we would have to use formulas that are beyond the scope of the GMAT ("tan" for example) http://planetmath.org/anglebetweentwolines but the point here, as I said above, is not to find the measure.

Agree that Tan and other trignometry concepts are out of the remit of GMAT but is the formula for angle between two lines m1-m2/1+m1m2 in scope ? In other words can this question come in PS section ?

Re: If lines y=mx+b and x=y+bm intersect at a degrees angle [#permalink]

Show Tags

20 Aug 2015, 19:59

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. _________________

Part 2 of the GMAT: How I tackled the GMAT and improved a disappointing score Apologies for the month gap. I went on vacation and had to finish up a...

Cal Newport is a computer science professor at GeorgeTown University, author, blogger and is obsessed with productivity. He writes on this topic in his popular Study Hacks blog. I was...

So the last couple of weeks have seen a flurry of discussion in our MBA class Whatsapp group around Brexit, the referendum and currency exchange. Most of us believed...