Question

Two sides $PQ$ and $QR$ of $∆PQR$ are $28cm$ and $38cm$ respectively. Find the length of its third side $PR$ if perimeter of $∆PQR$ is $100cm$​

Answer 1

Length of third side of $∆PQR$

Given, $PQ$$=$$28cm$

$QR$$=$$38cm$

Perimeter of triangle $=$$100cm$

$PQ+QR+PR$ $=$$100cm$

$\begin{array}{rcl}28+38+PR& =& 100\\ 66+PR& =& 100\\ PR& =& 100-66\\ PR& =& 34cm\end{array}$

Therefore, Length of third side $PR$ of $∆PQR$ is $34cm$.