April 20th, 2018, 04:15 AM  #1 
Banned Camp Joined: Dec 2017 From: Tel Aviv Posts: 87 Thanks: 3  trapezoid
I need to find a formula that use r to formulate the long side of the trapezoid (DC). Note: In the picture desribe = describe. 
April 20th, 2018, 05:12 AM  #2 
Newbie Joined: Sep 2013 From: Reno,NV Posts: 14 Thanks: 1 Math Focus: Number Theory 
Since ABDC, I would start with the Parallel Postulate

April 20th, 2018, 05:16 AM  #3 
Banned Camp Joined: Dec 2017 From: Tel Aviv Posts: 87 Thanks: 3 
A few things: 1.Question: What is the Parrallel Postulate? 2. How the terminology of circle that "locked" in the trapezoid? i write inscribe, but is it the right terminology? 3. I still don't know how to slove the problem? 
April 20th, 2018, 05:48 AM  #4 
Global Moderator Joined: Dec 2006 Posts: 19,291 Thanks: 1683 
Bisect angle BCD.

April 20th, 2018, 06:32 AM  #5 
Banned Camp Joined: Dec 2017 From: Tel Aviv Posts: 87 Thanks: 3 
still I don't know what to do.

April 21st, 2018, 05:24 PM  #6 
Member Joined: Jan 2016 From: Athens, OH Posts: 89 Thanks: 47 
I am irritated when a person posts the same question on multiple help forums. So if you want answers from me in the future, don't do this. Here's a solution to your problem. I leave it to you to supply the reasoning for each step. 
April 24th, 2018, 11:35 AM  #7 
Senior Member Joined: Feb 2010 Posts: 683 Thanks: 129 
or $\displaystyle b=2r \cdot \tan 55^{\circ}$


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