TomB wrote:
In the xy plane, each point on the circle k has non negative coordinates and the center of k is the point (4,7). What is the max possible area of K?
A. 4pi
B. 9pi
C. 16pi
D. 28pi
E. 49pi
This question is already posted in the forum. My doubt is why it cant be the 7. everybody is saying it could touch negative coordinates. please explain in detail
The circles with radius of 4 (blue) and 7 (red):
Attachment:
Circle.png [ 13.66 KiB | Viewed 13666 times ]
As you can see if the circle has the radius of 7 some of its points will be in II quadrant so will have negative x coordinate, but we are told that: "each point on the circle k has
non negative coordinates", so the radius of 7 is not possible (or any other radius more than 4).
So, the max radius is 4, which makes the max area equal to \(\pi{r^2}=16\pi\).
Answer: C.
Hope it's clear.
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