Question Number 224888 by Abdulazim last updated on 09/Oct/25
Commented by mr W last updated on 10/Oct/25
$${R}_{\Delta{PQR}} =\frac{{R}_{\Delta{ABC}} }{\mathrm{2}} \\ $$
Commented by mr W last updated on 10/Oct/25
https://en.wikipedia.org/wiki/Nine-point_circle