The total surface area of a hemisphere includes both the curved surface and the circular base:
A=2πr2+πr2=3πr2
To find the rate of change, differentiate with respect to r:
drdA=drd(3πr2)=3π⋅drd(r2)=3π⋅2r=6πr
Evaluate at r=31.331:
31.331=3103113=1011=1.1 cm
Substitute into our formula:
drdA=6πr=6π(1.1)=6.6π cm2/s
Therefore, the rate of change of the total surface area of the hemisphere with respect to radius at r=31.331 cm is 6.6π cm2/s.