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Math Help - circle theorem

  1. #1
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    circle theorem

    hi, i need to find X and Y on this circle:

    circle theorem-circle.jpg

    i know X= 62 but im unsure how to work out what Y would be.
    could someone please explain how i would work this out!

    thanks!
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  2. #2
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    Quote Originally Posted by andyboy179 View Post
    find X and Y on this circle:
    Click image for larger version. 

Name:	circle.jpg 
Views:	29 
Size:	9.7 KB 
ID:	20865
    i know X= 62
    If you do know that X=62 then there is something wrong with your drawing.
    According to that drawing the central angle is 131 not 124.
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  3. #3
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    sorry its my drawing, its not 131 its 31, i drew around the part which is 31
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  4. #4
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    Quote Originally Posted by andyboy179 View Post
    sorry its my drawing, its not 131 its 31, i drew around the part which is 31
    You have the wrong idea there.
    Look up inscribed angle and also centeral angles.
    Find out how their measures are found.
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  5. #5
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    will do but i will just let you know why i thought it is 61.
    i thougt it was 61 because i thought that the X angle is alwas double whatever is where 31 is, so 31 x2=62
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  6. #6
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    would x be 15.5 because the angle from center(31) is twice as big as circumferance.
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  7. #7
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    Quote Originally Posted by andyboy179 View Post
    would x be 15.5 because the angle from center(31) is twice as big as circumferance.
    That is correct.

    So y=\dfrac{360 - 2x}{2}.
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  8. #8
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    So Y=164.5??
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  9. #9
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    So would this mean y=164.5??
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  10. #10
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    circle theorem, finding Y

    hi,
    i need to work out what Y is on this circle theorem:
    circle theorem-circle.jpg

    to find Y would i do:

    360-31= 329
    329/2=164.5
    Y=164.5
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  11. #11
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    Quote Originally Posted by andyboy179 View Post
    hi,
    i need to work out what Y is on this circle theorem:
    Click image for larger version. 

Name:	circle.jpg 
Views:	34 
Size:	9.8 KB 
ID:	20892

    to find Y would i do:

    360-31= 329
    329/2=164.5
    Y=164.5
    Hi andyboy179,

    Your answer is correct. y = 164.5 degrees
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