Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

RolyPoly

  • one year ago

Circle problem

  • This Question is Closed
  1. RolyPoly
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Please refer to the attachment.

    1 Attachment
  2. RolyPoly
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Intuitively, I think I is correct. But I don't know how to ensure the other two are correct or not..

  3. DLS
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    3rd seems correct :P

  4. ZeHanz
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    I think you are right about I. The sum of the angles is always 1080 degrees. II is also right, because of this: imagine O is at height h above line CD. If you draw a horizontal line through O, it intersect both AC and BD, lets say in A' and B'. Then it is easy to see that triangles AA'O and BB'O are congruent. This means AA'=BB'=a. SO AC = h-a and BD = h+a, total length is 2h, so constant. U can use this also to reason whether ACxBC is constant or not!

  5. ZeHanz
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    TYPO: 180 deg ;)

  6. ZeHanz
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Why is ACxBD NOT constant? (so III is false).

  7. DLS
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    oh:o not constant yeah

  8. ZeHanz
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    (h+a)(h-a)=...

  9. sirm3d
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    |dw:1357564433476:dw|

  10. RolyPoly
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    So, C and D are not fixed point, i.e. they'll change when the diameter rotates. AC // BD, so theta + phi must be 180 degrees (int. angles, AC//BD) The two triangles are congruent (ASA), so both sides have the same (magnitude of) change. And AC+BD would remain constant as 2h. And the last point: AC x BD = (h-a)(h+a) = h^2 - a^2, which is not a constant. So, it's the answer. Thanks everyone!!!

  11. sirm3d
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yw.

  12. ZeHanz
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 2

    yw!

  13. DLS
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    like i said :3

  14. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.