geometry

[Infinite7]

What's the OA?

[Infinite7]

Originally Posted by touche

You are absolutely right!
No calculations needed in this case, where ever point P(X,Y) is, Q will be (y,x)!

I don't understand? Can someone explain to me, pls...

[eravi11]

OA is A.

[touche]

Originally Posted by Infinite7

I don't understand? Can someone explain to me, pls...

Infinite7, let me try.....though im not a maths student...
If P is -2,0 then Q is 2,0... likewise
if P is 0,2 then Q is 2,0

If two triangles were to be made by drawing P and Q to x axis....you will have a fixed hyp.

As the hypotenuse is constant the squares of the adjacent and opposite sides will always be equal.

or a1^2+b2^2=a2^2+b2^2
I guess one could prove it from here on....

a1^2-a2^2=b2^2-b1^2
(a1+a2)(a1-a2)=(b2+b1)(b2-b1).. lost here!
try taking values.... you will get what im trying to suggest!

[Infinite7]

Originally Posted by touche

Infinite7, let me try.....though im not a maths student...
If P is -2,0 then Q is 2,0... likewise
if P is 0,2 then Q is 2,0

If two triangles were to be made by drawing P and Q to x axis....you will have a fixed hyp.

As the hypotenuse is constant the squares of the adjacent and opposite sides will always be equal.

or a1^2+b2^2=a2^2+b2^2
I guess one could prove it from here on....

a1^2-a2^2=b2^2-b1^2
(a1+a2)(a1-a2)=(b2+b1)(b2-b1).. lost here!
try taking values.... you will get what im trying to suggest!

Ok I understood that part. But how do you know that the point Q is the reflection of the point P? I know those points are on the circle and the radii should be equal. But couldn't the point of Q be on any part of the plain (x and y being +ve)?

[MBAchase]

IMO (A).

[vgmat_24]

this is gmatprep question OA is A

[morpheus1976]

Originally Posted by touche

You are absolutely right!
No calculations needed in this case, where ever point P(X,Y) is, Q will be (y,x)!

How did you come to this conclusion?

Thanks

[touche]

Originally Posted by morpheus1976

How did you come to this conclusion?

Thanks

Sorry, wrong conclusion, that would happen in only 3 situations!

[ahsan400]

IMO-A