In \(\Delta ABC\), a circle touches side \(BC\) at \(P\) and the extended sides \(AB\) and \(AC\) at \(Q\) and \(R\), repectively. Verify that \(AQ = \frac{1}{2}(AB + BC + CA)\)
 
Proof:
 
YCIND_240308_6083_circles_10.png
 
Lengths of two tangents drawn from an to a circle are .
 
\(BQ = \) - - - - (i)
 
 
\(PC =  \) - - - - (ii)
 
\(AQ =  \) - - - - (iii)
 
From (iii), we have
 
\(AB +\) \(= AC + \)
 
\(AB + \)\( = AC + \) (using (i) and (ii))
 
Perimeter of \(\Delta ABC = \)
 
By substituting and simplifying the terms we get,
 
\(AQ = \frac{1}{2}(AB + BC + CA)\)
 
 Hence proved.