In the rectangular coordinate system, are the points (a, b) and (c, d) equidistant from the origin?
(1) a/b = c/d
(2) root (a^2)+root (b^2) = root (c^2) + root (d^2)
oa c, but shldnt it be e
DS .. equi distance geo
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st two can be written as |a|+|b| = |c|+|d|
sqare root of (x^2) means |x|
now square both sides and use st 1 ull see a^2 + b^2 = c^2 + d^2
sqare root of (x^2) means |x|
now square both sides and use st 1 ull see a^2 + b^2 = c^2 + d^2
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I am getting E, as per previous post of youngwolf..
Any thoughts?
Any thoughts?
youngwolf wrote:a^2+2*|a|*|b|+b^2=c^2+2*|c|*|d|+d^2sumithshah wrote: now square both sides and use st 1 ull see a^2 + b^2 = c^2 + d^2
first statement a/b=c/d or a*d=b*c
I don't see how you get a^2 + b^2 = c^2 + d^2
Please explain.
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My bad, I was thinking AD = BC was given. But he answer is STILL C.
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(1) a/b = c/d
(2) sqrt(a^2) + sqrt(b^2) = sqrt(c^2) + sqrt(d^2)
Ok,
1 is clearly not sufficient. Let's write 2 as
|a|+|b| = |c|+|d| , this is not sufficient since it can have many solutions. Now multiply both sides with |d|
|a||d|+|b||d| = |c||d|+|d||d|..................call it 3
Fom 1, ad=bc, so |a||d| = |b||c|
Replacing in our equation 3
|b||c|+|b||d| = |c||d|+|d||d|
|b| (|c|+|d|) = |d| (|c|+|d|)
Hence, |b| = |d|, and using 1 with this, |a| = |c|
So a,b and c,d have same values of co-ordinates if signs are ignored.
Since ditance from origin is square root of sum of squares of x and y co-ordinates, these 2 are equidistant from origin.
So, C is the answer.
Picked from Mgmat forum
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(1) a/b = c/d
(2) sqrt(a^2) + sqrt(b^2) = sqrt(c^2) + sqrt(d^2)
Ok,
1 is clearly not sufficient. Let's write 2 as
|a|+|b| = |c|+|d| , this is not sufficient since it can have many solutions. Now multiply both sides with |d|
|a||d|+|b||d| = |c||d|+|d||d|..................call it 3
Fom 1, ad=bc, so |a||d| = |b||c|
Replacing in our equation 3
|b||c|+|b||d| = |c||d|+|d||d|
|b| (|c|+|d|) = |d| (|c|+|d|)
Hence, |b| = |d|, and using 1 with this, |a| = |c|
So a,b and c,d have same values of co-ordinates if signs are ignored.
Since ditance from origin is square root of sum of squares of x and y co-ordinates, these 2 are equidistant from origin.
So, C is the answer.
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- logitech
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well, we know the ratios of (a/b) is equal to (c/d) so it means that they might have different signs (-/-) = (+/+) or same signs such as (+/+) = (+/+) ---> HINT 1 ( equal ratios) + HINT 2 ( they might or not have same signs )
and we know that the sum of their absolute values are the same!
since absolute values are always + numbers
Hence, |b| = |d| & |a| = |c|
Hope this approach helps to simply this question for you.
and we know that the sum of their absolute values are the same!
since absolute values are always + numbers
Hence, |b| = |d| & |a| = |c|
Hope this approach helps to simply this question for you.
LGTCH
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In the rectangular coordinate system, are the points (a, b) and (c, d) equidistant from the origin?
(1) a/b = c/d
(2) root (a^2)+root (b^2) = root (c^2) + root (d^2)
i did it this way....
(1) a/b = c/d
adding 1 to both sides, we get
(a/b)+1 = (c/d)+1
(a+b)/b=(c+d)/d ----(A)
from (2)
root (a^2)+root (b^2) = root (c^2) + root (d^2)
it can be simplied as
a+b=c+d ---(B)
(irrespective of if they are +ve or -ve numbers)
from (A) and (B), if numerators are same, then numerators must be same
ie b=d ---(C)
from (C) and (B) we get
a=c
So the points (a, b) and (c, d) equidistant from the origin.
Did I missed out on something by not considering the sign of the numbers here?