Dallasb22
Given: DR tangent to Circle O.
If (measure of)DB = 150°, then (angle)A = ?degrees.
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Dallasb22
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Dallasb22
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@CliffSedge
CliffSedge
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More of these shenanigans, eh?
Dallasb22
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Hehe, yup.
CliffSedge
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Which angle is 150º?
Dallasb22
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Arc DB is 150 degrees
CliffSedge
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Oh that's for the arc, ok. then that means that angle BCD is half of that because it is an inscribed angle cutting the same arc.
CliffSedge
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(I'm assuming from the picture that you mean arc BAD and not arc BCD, since it could go either way around the circle.)
Dallasb22
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Yes sorry about that, that's how they put it in on the sheet.
CliffSedge
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I think the easiest way to find A is the same property: inscribed angles are half of the arc they cut, so if arc BAD is 150, then arc BCD is the other part of the circle (the whole thing is 360º remember).
Dallasb22
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Yes arc BCD is 210
So angle A is: 105 degrees
CliffSedge
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Exactly.