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Lines- intersecting angles (m08q15) [#permalink]
 07 Jul 2008, 20:44
Question Stats:
58% (01:51) correct
41% (01:59) wrong based on 1 sessions
At what angle do the lines y = Kx + L and x = y + KL intersect? 1. K = 22. K = LSource: GMAT Club Tests - hardest GMAT questions
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Re: Lines- intersecting angles [#permalink]
07 Jul 2008, 21:38
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line equation y = mx + c
m1 = K
m2 = 1
angle between lines = A
tan(A) = m1*m2
statement 1 : K = 2, we can find m1*m2 = 2 Suff
statement 2: doesnt give us value of K. Not suff
Answer A
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 08:36
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By 1st condition we can form the two equations as Y=2X+L and Y=X-2L so solving the two equations we get the values of X and Y which gives the intersection points of the two lines. So sufficient By 2nd condition we ket the two equations as Y=Lx+L and Y=X-Lsqr2 which will not help to solve the two equations so not sufficient And combinig the two equations we will not get any additional information other than what we gt in the 1st equations so A is the correct ans aaron22197 wrote: At what angle do the lines y = Kx + L and x = y + KL intersect?
1. K = 2
2. K = L
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Re: Lines- intersecting angles [#permalink]
07 Jul 2008, 21:21
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aaron22197 wrote: At what angle do the lines y = Kx + L and x = y + KL intersect?
1. K = 2
2. K = L Is A right? y=Kx+L y=x-KL To determine the angle, we just need the slopes of the lines.
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 08:47
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i think this should be C?
cause we dont know if these lines intersect if at all??
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 08:50
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If you manipulate the equations to make them in the same form as line functions, we see: y = Kx + Land y = x - KLOnce we know that K = 2 and not 1, we know the lines are not parallel. The only way we would know that the lines do not intersect is if they are parallel...otherwise, somewhere the lines must intersect. If Kx = x, then the slope would be the same and the lines would be parallel. fresinha12 wrote: i think this should be C?
cause we dont know if these lines intersect if at all??
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 08:59
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you are right.. i m having a slow day..its like my Q skills are degrading by the day...grrrr i should take this sucker before i drop below 49 on Q...if only i can improve my V to 40+ jallenmorris wrote: If you manipulate the equations to make them in the same form as line functions, we see: y = Kx + Land y = x - KLOnce we know that K = 2 and not 1, we know the lines are not parallel. The only way we would know that the lines do not intersect is if they are parallel...otherwise, somewhere the lines must intersect. If Kx = x, then the slope would be the same and the lines would be parallel. fresinha12 wrote: i think this should be C?
cause we dont know if these lines intersect if at all?? |
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 09:25
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You'll be fine. Do you have it scheduled yet? Mine is 7/25. I think I can bring my Q up from 42 to about 45 - 48, that should be what I need. My verbal was 38 when I took it, but have studied a lot on it and that's my strenght, so improving to a 43 - 47 should be possible. My highest goal is a 47-47 split which should put me around a 750. I've been getting 46-48 in my quant and have been focusing on it mainly. I'll be taking the GMATPrep 2 this weekend. I'm looking for a low to mid 700s on the GMATPrep2. I saw the picture of your NYC meeting with Walker, GMATBlackbelt, uphillclimb, and others...where did you guys meet? Looks like you all had a great time. Allen fresinha12 wrote: you are right.. i m having a slow day..its like my Q skills are degrading by the day...grrrr i should take this sucker before i drop below 49 on Q...if only i can improve my V to 40+ jallenmorris wrote: If you manipulate the equations to make them in the same form as line functions, we see: y = Kx + Land y = x - KLOnce we know that K = 2 and not 1, we know the lines are not parallel. The only way we would know that the lines do not intersect is if they are parallel...otherwise, somewhere the lines must intersect. If Kx = x, then the slope would be the same and the lines would be parallel. fresinha12 wrote: i think this should be C?
cause we dont know if these lines intersect if at all?? _________________
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 07:05
I agree that the answer is A. We need to know the slope. The y-intercept doesn't matter (K=L). That tells us nothing because we still don't know what K is, and that's the only way we can know it's relationship to the slope of the other line. If we know that K = 2 and then x is a slope of 1. The other, all we know if K=L. If we were told the Y intercept for one of the lines, #2 would be sufficient, but as is, it is insuffiicient.
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 10:15
Answer A.
intersecting angle can be found by tan@ = (m1-m2)/(1-m1m2)
(experts please guide me if anybody can find angle b/w two intersecting lines with out using tan@ even though gmat does not support trignometry)
so considering first line
y=kx +L --- m1 = k
x = y+KL --- m2 = 1
so tan@ = k-1/k+1
so we need K value here, tan@ = 1/3 -- which can be some angle.. so we can find angle with A SUFFICIENT
For B,
K=L,
it doesn't make big difference so INSUFFICIENT
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Re: Lines- intersecting angles [#permalink]
08 Jul 2008, 14:02
aaron22197 wrote: At what angle do the lines y = Kx + L and x = y + KL intersect?
1. K = 2
2. K = L Slope of line 1 = K slope of line 2 = 1 We need to find K (1) suff (2) insuff A
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Re: Lines- intersecting angles (m08q15) [#permalink]
14 Nov 2009, 00:09
A for me.
For the same slope, it does not matter what L is. The two lines always intersect at the same angle
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Re: Lines- intersecting angles (m08q15) [#permalink]
20 Mar 2010, 16:02
Few things :- Is the correct formula to find the angle is tan@ = (m1-m2)/(1-m1m2) and is there another way to find the angle ?
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Re: Lines- intersecting angles (m08q15) [#permalink]
04 Jun 2010, 06:40
I will choose option A as this gives the slope (m).
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Re: Lines- intersecting angles (m08q15) [#permalink]
04 Jun 2010, 08:12
I think the correct formula for calculating angle is tan@= (m1-m2)/(1+m1m2)
Please correct me if I'm wrong
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Re: Lines- intersecting angles (m08q15) [#permalink]
04 Jun 2010, 09:57
I knew that all we needed the slope but for some reason I thought the y-intercept was important.
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Re: Lines- intersecting angles (m08q15) [#permalink]
10 Jun 2010, 15:15
Irrespective of the formula, the intersecting angle requires a knowledge of the two slopes (gradients) - M1 and M2
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Re: Lines- intersecting angles (m08q15) [#permalink]
08 Jun 2011, 18:14
A for me too.. Using the slope concept..Once we know that the lines arent parallel, we have our answer.
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Re: Lines- intersecting angles (m08q15) [#permalink]
10 Jun 2011, 03:31
A seems to be the right answer
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Re: Lines- intersecting angles (m08q15) [#permalink]
16 Jun 2011, 06:45
1st is suffiient..... lines are perpendicular if the slope is opposite signs and reciprocal to each other. 2nd is not sufficient So answer is A
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Re: Lines- intersecting angles (m08q15)
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16 Jun 2011, 06:45
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