Question

Two circles of radii $5.5cm$ and $4.2cm$ touch each other externally. Find the distance between their centres.
Let the two circles having centres $P$ and $R$ touch each other externally at point $Q$.
Here, $PQ=5.5cm,QR=4.2cm$
The two circles touch each other externally.
$\therefore$ By theorem of touching circles,
$$\begin{array}{cc}& P-Q-R\\ & PR=PQ+QR\\ & =5.5+4.2\\ & =9.7cm\end{array}$$
[The distance between the centres of the circles touching externally is equal to the sum of their radii]

Answer 1

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