http://testpak.starssuite.com/files/Geo2…
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Notice that angle A in the triangle is 180° - 60° - 60° = 60°.
If we forget about side BC, then we can think of sides AC and BC as two secant lines in the circle; since this is the case, angle A's intercepted arc, which is CB, will have an angle twice of that as A. Therefore, the measure of arc CB is 2(60°) = 120°.
I hope this helps!
If we forget about side BC, then we can think of sides AC and BC as two secant lines in the circle; since this is the case, angle A's intercepted arc, which is CB, will have an angle twice of that as A. Therefore, the measure of arc CB is 2(60°) = 120°.
I hope this helps!