(c) Required area $= 2\int_{0}^{a}{\sqrt{4ax}dx}$ $= 4\sqrt{a} \times \frac{2}{3}\left\lbrack x^{3/2} \right\rbrack_{0}^{a} = \frac{8}{3}a^{2}\ sq\ unit$
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.