# Geometry: I want to understand some points

#### irony of truth

What is my unknown (say x) if I am finding the value in which an arc of a great circle 10 units long recedes from its chord? (given radius R and angle alpha?)

Here's my figure as an attachment...

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#### EnumaElish

Homework Helper
I am guessing, you can express R = xR + (1-x)R where (1-x)R is the height of your (isosceles) triangle and xR is the bit from the chord to the circle.

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#### HallsofIvy

What do you mean by "recedes from its chord"?

#### irony of truth

HallsofIvy, seems like the arc is moving away from its respected chord (form by the two enddpoints of the arc)

My friend told me that x = R - R cos (alpha)... I wonder why....

#### mukundpa

Homework Helper
He has given the greatest distance between the arc and the chord i.e. the difference of the radius and distance of the chord from the center

#### gopi krishna

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"Geometry: I want to understand some points "

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