Question

Hi guys,
In the question "It is given that P (0, 3), Q(7, 5), R(9, -2) and S are vertices of a square. A circle A passes through the points P, Q, R and S. Find the equation of this circle. Hence or otherwise find the equation of circle B which is the image of A under the reflection about y – axis."

Can someone help me with the part hence or otherwise? I've found that the equation of the circle is x^2 + y^2 -9x -y -6 =0

Thanks =)

Answers

drwls
Assuming your answer is correct, it can be written

(x - 9/2)^2 + (y - 1/2)^2 = 106/4

(check my numbers)

The reflection about the y axis would be

(x + 9/2)^2 + (y - 1/2)^2 = 106/4
Joshua
Hi drwls,
Just wondering, does the word "under" in the question influence the question at all?

Thanks for your reply! =)
drwls
In this mathematics context, "Under the reflection about (an axis)" is the same as saying "after a reflection about (an axis)"

Mathematicions often us the preposition "under" to indicate carrying out an operation. It does not mean "below" in this case.
Joshua
Thanks drwls for the good explanation =)
mina
jack has 3/4 of a dollar. Maxwell has 1/10 of a dollar. Do they have more or less than $1.oo in all?

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