dux3000 Posted September 10, 2015 Share Posted September 10, 2015 For this question (http://www.greenlighttestprep.com/module/gre-geometry/video/889) I understand the video solution however when I solved it, I used the fact that angle AOB = angle ADB to get A (50 degrees) as my answer. Not sure what happened Link to comment Share on other sites More sharing options...
Eigen Posted September 10, 2015 Share Posted September 10, 2015 (edited) Angle AOB does not = angle ADB.ABO is 90, so AOB is 50. AOB + BOD = 180, so BOD = 130. OB and OD are both the same length (radii of circle), so OBD = ODB = 180-130/2 = 25.OBC = 90, so OBD + DBC = 90, or DBC = 65.::edit:: Just realized my solution was the same as the video (didn't watch it). So what exactly are you asking? Edited September 10, 2015 by Eigen Link to comment Share on other sites More sharing options...
dux3000 Posted September 10, 2015 Author Share Posted September 10, 2015 I thought there was a rule I learned in highschool that says if you have a tangent line then you get an isosceles triangle (so angle AOB = angle ADB). BUT I just looked it up and I'm wrong. It has to do with having 2 tangent lines from the same point. Back to studying!!Thanks though Link to comment Share on other sites More sharing options...
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