The Total solution for NCERT class 6-12
Answer - 31 : -
Radius of inner circle = rWidth of path = hтИ┤ Outerradius (R) = (r + h)тИ┤ Areaof path = ╧АR2┬атАУ ╧Аr2= ╧А {(r + h)2┬атАУ r2}= ╧А {r2┬а+ h2┬а+2rh тАУ r2}= ╧А {2rh + h2}= ╧Аh (2r + h) Hence proved.