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#### Albert

##### Well-known member

- Jan 25, 2013

- 1,225

$and,\,\, 2\overline{BD}=\overline{CD},\,\, \angle DAB=15^o$

$find :\,\, \angle ACB=?$

- Thread starter Albert
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- Thread starter
- #1

- Jan 25, 2013

- 1,225

$and,\,\, 2\overline{BD}=\overline{CD},\,\, \angle DAB=15^o$

$find :\,\, \angle ACB=?$

- Mar 10, 2012

- 834

Find a point $M$ between $A$ and $D$ such that $\angle MBD=30$. Note that $MD=DM$ and $AM=MB$. Say $BD=1$. The above leads to $AD=\sqrt 3 + 1$. Further note that $\angle CMD=90$ and hence $\angle MCA=45$. Consequently $\angle ACB=75$.

$and,\,\, 2\overline{BD}=\overline{CD},\,\, \angle DAB=15^o$

$find :\,\, \angle ACB=?$

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- #3

- Jan 25, 2013

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caffeinemachine :very good solutionFind a point $M$ between $A$ and $D$ such that $\angle MBD=30$. Note that $MD=DM$ and $AM=MB$. Say $BD=1$. The above leads to $AD=\sqrt 3 + 1$. Further note that $\angle CMD=90$ and hence $\angle MCA=45$. Consequently $\angle ACB=75$.

- Mar 10, 2012

- 834

Thanks. If you have a different one then please post it.caffeinemachine :very good solution

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- #5

- Jan 25, 2013

- 1,225

- Mar 10, 2012

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Awesome!