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Hi, it would mean so much to me if someone helped me with this problem:

Let B, A, and D be three consecutive vertices of a regular 18-gon. A regular heptagon is constructed on AB with a vertex C next to A. Find angle BCD.

 

Thanks!

 May 25, 2020
edited by Caffeine  May 25, 2020
 #1
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I solve this using coordinates:

 

A = (1,0)

B = (0.924328, 0.471208)

C = (1.222783, -1.147542)

D = (0.924328, -0.471208)

 

==> angle BCD = 75 degrees

 May 25, 2020
 #2
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I got 80 degrees. Is that correct?

 May 25, 2020
edited by Caffeine  May 25, 2020

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