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#1 Re: Help Me ! » Circles: Chords, Radii, and Arcs » 2016-06-10 02:42:39

12. D >> AC = AB / sin 30 = 4 / 1/2 = 8; r = AC / 2 = 4
13. E >> let's name circle center D and DB = DA > ADB is an equilateral triangle with ABD = BAD = ADB = 60
14. D (similar to #13 but with isosceles triangle)
19. E >>I'm not sure but no matter where I put this point D, the angle seems always to be 90.
20. D >> AC = √BC 2 + AB 2= √ 900 = 30; r = 15

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