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None of the answer choices above is correct, clearly; there should be a Pi in each, presumably. I know the source of the question, and it's their mistake, not jsl's. In any case, if the x-intercepts are 8 apart, by symmetry they must be at (-3, 0) and (5, 0); that is, the x-co-ordinates of the intercepts must be 4 to the left and right of x=1, the x-co-ordinate of the centre of the circle. This is easier to see if you draw a diagram in the co-ordinate plane. Once you know these points on the circle, you can find that the distance to the centre is 5, so the circle's radius is 5. The area is then Pi*(5)^2 = 25*Pi.jsl wrote:A circle lies in an X-Y plane, with its center at (1, -3). If the distance between the X-intercepts of the circle is 8 units, what is the area of the circle?
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Just one confusion Ian,Ian Stewart wrote:None of the answer choices above is correct, clearly; there should be a Pi in each, presumably. I know the source of the question, and it's their mistake, not jsl's. In any case, if the x-intercepts are 8 apart, by symmetry they must be at (-3, 0) and (5, 0); that is, the x-co-ordinates of the intercepts must be 4 to the left and right of x=1, the x-co-ordinate of the centre of the circle. This is easier to see if you draw a diagram in the co-ordinate plane. Once you know these points on the circle, you can find that the distance to the centre is 5, so the circle's radius is 5. The area is then Pi*(5)^2 = 25*Pi.jsl wrote:A circle lies in an X-Y plane, with its center at (1, -3). If the distance between the X-intercepts of the circle is 8 units, what is the area of the circle?
9
16
25
36
64
The center is at (1, -3), and (5,0) is a point on the circle, The distance from (1, -3) and (5,0) is 5, not 4 (draw the picture; you should get a 3-4-5 triangle).gmat009 wrote:Just one confusion Ian,Ian Stewart wrote:None of the answer choices above is correct, clearly; there should be a Pi in each, presumably. I know the source of the question, and it's their mistake, not jsl's. In any case, if the x-intercepts are 8 apart, by symmetry they must be at (-3, 0) and (5, 0); that is, the x-co-ordinates of the intercepts must be 4 to the left and right of x=1, the x-co-ordinate of the centre of the circle. This is easier to see if you draw a diagram in the co-ordinate plane. Once you know these points on the circle, you can find that the distance to the centre is 5, so the circle's radius is 5. The area is then Pi*(5)^2 = 25*Pi.jsl wrote:A circle lies in an X-Y plane, with its center at (1, -3). If the distance between the X-intercepts of the circle is 8 units, what is the area of the circle?
9
16
25
36
64
How we got this radius 5. IMO radius shud be 4.
Circle has centre at (1,-3) so radius shud be 4 instead of 5.
Plz. explain this.......
Got it.....Ian Stewart wrote:The center is at (1, -3), and (5,0) is a point on the circle, The distance from (1, -3) and (5,0) is 5, not 4 (draw the picture; you should get a 3-4-5 triangle).gmat009 wrote:Just one confusion Ian,Ian Stewart wrote:None of the answer choices above is correct, clearly; there should be a Pi in each, presumably. I know the source of the question, and it's their mistake, not jsl's. In any case, if the x-intercepts are 8 apart, by symmetry they must be at (-3, 0) and (5, 0); that is, the x-co-ordinates of the intercepts must be 4 to the left and right of x=1, the x-co-ordinate of the centre of the circle. This is easier to see if you draw a diagram in the co-ordinate plane. Once you know these points on the circle, you can find that the distance to the centre is 5, so the circle's radius is 5. The area is then Pi*(5)^2 = 25*Pi.jsl wrote:A circle lies in an X-Y plane, with its center at (1, -3). If the distance between the X-intercepts of the circle is 8 units, what is the area of the circle?
9
16
25
36
64
How we got this radius 5. IMO radius shud be 4.
Circle has centre at (1,-3) so radius shud be 4 instead of 5.
Plz. explain this.......
