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September 15th, 2016, 11:02 AM  #1 
Senior Member Joined: Jan 2015 From: London Posts: 108 Thanks: 2  Trigonometry and Circle Properties https://images1.discordapp.net/.eJw...bO7Gg4azXvZTZ4 I have done 3, a b and c but I can't do d. How do I get the angle of d? answers to a)87 b)53.1 c)90 
September 15th, 2016, 12:24 PM  #2 
Senior Member Joined: Jan 2015 From: London Posts: 108 Thanks: 2 
I missread c sorry i got that wrong ? can anyone help?

September 15th, 2016, 12:58 PM  #3 
Math Team Joined: Jul 2011 From: Texas Posts: 2,820 Thanks: 1464 
see attached thumbnail ...

September 15th, 2016, 01:01 PM  #4 
Senior Member Joined: Aug 2016 From: morocco Posts: 273 Thanks: 32 
d) angle ADB=180 angle BDO =180 angle OBD since OD=OB. Last edited by abdallahhammam; September 15th, 2016 at 01:08 PM. 
September 15th, 2016, 01:07 PM  #5 
Senior Member Joined: Jan 2015 From: London Posts: 108 Thanks: 2 
so for 4a and b are both 9.91 but for c how would you find out the angle A ? don't you need another angle in order to do that?

September 15th, 2016, 01:12 PM  #6 
Senior Member Joined: Aug 2016 From: morocco Posts: 273 Thanks: 32 
cos(OAB)=AB/OA=116/145.


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circle, properties, trigonometry 
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