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Hi everyone! I am new to this website and I need a bit of help with this problem.  I do not need you to answer the problem for me, just walk me through a few steps/hints and I will try to solve it on my own.

In triangle ABC, AB = AC, and angle A is equal to 36 degrees. Point D is on line AC so that line BD bisects angle ABC.


(a) Prove that BC = BD = AD.

(b) Let x = BC and let y = CD. Using similar triangles BCD and ABC, write an equation involving x and y.

(c) Let r = \frac{y}{x}. Write the equation from Part (b) in terms of r, and find r.

(d) Find cos(36) and cos(72) using Parts a-c.

This is a problem from the Introduction to Geometry course at Art of Problem Solving.

 

I have currently solved parts (a) through (c).

 Jun 17, 2020
 #1
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Do not cheat on your AoPS homework.

 Jun 17, 2020
 #2
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I'm not trying to cheat, I am just asking for help as for what to do next...

 Jun 17, 2020

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