Here's the question you clicked on:
richardlong369
Look at atachment
area of shaded=area of large circle-area of small circle are of large circle=pi*R^2=pi(18)^2=324pi area of small circle=area of large circle-areae shaded pi*r^2=324pi-150pi pi*r^2=174pi r^2=174 r=13.9
Thankyou that helped a lot