The lateral surface area of a cone of radius r and height h (the surface area excluding the base) is A=pir . Find dr/dh for a cone with lateral surface area of A = 4500picm2. Evaluate this derivative when r = 60 cm and h = 45 cm. dr/dh= cm3 Solution 4500=rsqrt(r2+h2) 2025*10^4=r^4+r^2 h^2 0= 4r^3 dr/dh +2rh^2dr/dh+2r^2h dr/dh=-rh/2r^2+h^2 =-45*60/2*3600+2025 =-0.292.