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Math Help - Define the relationship of two radii

  1. #1
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    Define the relationship of two radii

    Hello, this is probably an easy thing for most of you but I just can't find the jist of this problem.

    There's two circles perpendicular intersecting each other, C1 and C2. C1 intersects the connecting line between the centre points of C1 and C2 at the midpoint of the radius of C2. I am to define the relationship of the radii when r2 : r1 = 4 : ?

    I'm just not sure how I am supposed to define it. I'm guessing I should use a right-angled triangle to determine the unknown.
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  2. #2
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    Hello,

    what do you call "circles perpendicular intersecting each other" ? You mean they're tangent ?
    If so, how can C1 possibly intersect at half the radius of C2 ?
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  3. #3
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    Quote Originally Posted by DocBane View Post
    Hello, this is probably an easy thing for most of you but I just can't find the jist of this problem.

    There's two circles perpendicular intersecting each other, C1 and C2. C1 intersects the connecting line between the centre points of C1 and C2 at the midpoint of the radius of C2. I am to define the relationship of the radii when r2 : r1 = 4 : ?

    I'm just not sure how I am supposed to define it. I'm guessing I should use a right-angled triangle to determine the unknown.
    If two circles intersect orthogonally (I assume that's what is meant by "perpendicular intersecting") then the radius of one circle at the point of intersection is tangent to the other circle. Use the tangent-secant theorem to get an equation connecting the two radii.
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  4. #4
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    Thank you guys. I wasn't exactly sure what the question even meant when it said the circles intersect perpendicular/at a perpendicular. Note I'm Finnish and the question was in Finnish . The radii being tangents to each others' circles makes perfect sense. Again, thank you.
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