Re: HSC 2013 4U Marathon
A nice circle geo question
\\$Two circles with centres O and P and radii r and s (where r $<$ s) respectively touch externally at T. ABC and ADE are common tangents to the two circles.\\\\a) Show that A, O, T and P are collinear\\b) Show that AO = $\frac{r(r+s)}{s-r}