Question 21
Circles with centers $P,$ $Q$ and $R,$ having radii $1,$ $2$ and $3,$ respectively, lie on the same side of line $l$ and are tangent to $l$ at $P',$ $Q'$ and $R',$ respectively, with $Q'$ between $P'$ and $R'.$ The circle with center $Q$ is externally tangent to each of the other two circles. What is the area of $\triangle PQR?$