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# Math: Circles

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General Discussion
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great post!
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Excellent Info.

+1
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• If you know the length of the minor arc and radius, the inscribed angle is: 90L/nr

Please correct me if i am wrong but i think the formula should be : 180L/nr
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Waoooooo

Thanks a lot.
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Please note that the theorem of intersecting cords has a mistake. For math newbies, it could be dangerous. The same mistake is repeated in the iPhone App.

Posted from GMAT ToolKit
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Abhicoolmax,

Thanks for reporting. I think there is a mistake in image only in GMAT ToolKit.
We are going to submit 1.3.7. update today and I will add the image from the thread.
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thanks, great post !
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• An inscribed angle is exactly half the corresponding central angle. Hence, all inscribed angles that subtend the same arc are equal. Angles inscribed on the arc are supplementary. In particular, every inscribed angle that subtends a diameter is a right angle (since the central angle is 180 degrees).

Can anyone explain me the text in red?

Thanks
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tingle15 wrote:
• An inscribed angle is exactly half the corresponding central angle. Hence, all inscribed angles that subtend the same arc are equal. Angles inscribed on the arc are supplementary. In particular, every inscribed angle that subtends a diameter is a right angle (since the central angle is 180 degrees).

Can anyone explain me the text in red?

Thanks

The maximum central angle is 180 degrees and the maximum inscribed angle is 90 (exactly half of the corresponding central angle).

Angles inscribed on the arc are supplementary means that the angles adds to 180 degree. Two angles are supplementary if the sum of their angles equals 180 degree.

I found this URL useful -- https://www.mathopenref.com/arccentralangletheorem.html Have a look.
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Now I am confused. Shouldn't the statement say that -- Angles inscribed on the arc are [highlight]complementary[/highlight] since the maximum value of the inscribed angle can be 90 degree only.
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tingle15 wrote:
• An inscribed angle is exactly half the corresponding central angle. Hence, all inscribed angles that subtend the same arc are equal. Angles inscribed on the arc are supplementary. In particular, every inscribed angle that subtends a diameter is a right angle (since the central angle is 180 degrees).

Can anyone explain me the text in red?

Thanks

Supplementary angles are two angles that add up to 180°.

Complementary angles are two angles that add up to 90°.

Two angles inscribed on the arc (one from the one side and one from the another) are supplementary, they add up to 180° (on the diagram alpha and the angel opposite to alpha add up to 180°).

Hope it's clear.
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hey thanx a lot bunuel for these circles!!as i needed bit more material for concepts...
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Thanks for the concepts..
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The post is just awesome....!! Thanks once again Bunuel...!
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Just came across this, great stuff!
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