GEOMETRY

Discussion on Bangladesh Mathematical Olympiad (BdMO) National
User avatar
SANZEED
Posts:550
Joined:Wed Dec 28, 2011 6:45 pm
Location:Mymensingh, Bangladesh
GEOMETRY

Unread post by SANZEED » Wed Jan 18, 2012 11:54 pm

SECONDARY GEOMETRY (OWN)
Let a circle $[_{1}$ be drawn through the vertices $A,B$ of $triangle_ ABC$ touching $BC$ at $B$. Similarly drtaw the circle $[_{2}$ passing through $A,C$ touching $BC$ at $C$.Cord $AB$ produces an angle of $45^0$ at the center of $[_{1}$. Cord $AC$ produces an angle of $60^0$ at the center of $[_{2}$.If the radii of $[_{1}$ and $[_{2}$ are 5 & 7 respectively, then find the area of $triangle_ABC$.
$\color{blue}{\textit{To}} \color{red}{\textit{ problems }} \color{blue}{\textit{I am encountering with-}} \color{green}{\textit{AVADA KEDAVRA!}}$

User avatar
Phlembac Adib Hasan
Posts:1016
Joined:Tue Nov 22, 2011 7:49 pm
Location:127.0.0.1
Contact:

Re: GEOMETRY

Unread post by Phlembac Adib Hasan » Thu Jan 19, 2012 12:21 pm

$AB=\sqrt{2.5^2\frac {\sqrt {2}-1} {\sqrt {2} } },AC=\sqrt {2.7^2 \frac {1} {2} }$ [cosine rule]

$ \angle ABC=22.5^0, \angle ACB=30^0 $

So $\angle BAC=127.5^0 $

So $ (\triangle ABC)=\frac {1} {2} \sqrt{2.5^2\frac {\sqrt {2}-1} {\sqrt {2} } } \sqrt {2.7^2 \frac {1} {2} }\; sin\; 127.5^0 $.
Welcome to BdMO Online Forum. Check out Forum Guides & Rules

User avatar
nafistiham
Posts:829
Joined:Mon Oct 17, 2011 3:56 pm
Location:24.758613,90.400161
Contact:

Re: GEOMETRY

Unread post by nafistiham » Thu Jan 19, 2012 2:09 pm

SANZEED wrote:SECONDARY GEOMETRY (OWN)
Let a circle $[_{1}$ be drawn through the vertices $A,B$ of $triangle_ ABC$ touching $BC$ at $B$. Similarly drtaw the circle $[_{2}$ passing through $A,C$ touching $BC$ at $C$.Cord $AB$ produces an angle of $45^0$ at the center of $[_{1}$. Cord $AC$ produces an angle of $60^0$ at the center of $[_{2}$.If the radii of $[_{1}$ and $[_{2}$ are 5 & 7 respectively, then find the area of $triangle_ABC$.
try to use the equation editor ;)
\[\sum_{k=0}^{n-1}e^{\frac{2 \pi i k}{n}}=0\]
Using $L^AT_EX$ and following the rules of the forum are very easy but really important, too.Please co-operate.
Introduction:
Nafis Tiham
CSE Dept. SUST -HSC 14'
http://www.facebook.com/nafistiham
nafistiham@gmail

Post Reply