#How to calculate radius, and arc length of outermost arc?? ( See figure)

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cerulean marten
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Consider two concentric circles, centered at A. Now create a quadrant, such that it creates a quadrant for both the circles. Now create the angle bisector of angle EAC, that bisects the arc of outer circle at H and the inner circle arc at F, and extrude it to D. Then create a semi-circular arc EDC out side the outer circle.
Measurements given:
FD = 20 units.
Radius of inner circle = 1.9
Is it possible to solve for the radius of the outer circle, and the lenth of the semi-circular arc EDC? If no, what more measurements would I need?

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untold kilnBOT
stone flame
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Hint: Note that you can find AD given the information you have, and that'll be equal to (if we let the center of the semicircle be O) AO + OD. You can then find formulae for AO and OD in terms of the radius of the outer circle

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@cerulean marten