Solución

a.   A(t)=A(r(t))=π(65t2+1)2A(t)=A(r(t))=\pi \cdot {\left(6−\frac{5}{t^2+1}\right)}^2
b.   Exacto: 121π4\frac{121\pi}{4};   aproximadamente 95 cm2cm^2
c.   C(t)=C(r(t))=2π(65t2+1)C(t)=C(r(t))=2\pi\left(6−\frac{5}{t^2+1}\right)
d.   Exacto: 11π11\pi;   aproximadamente 35 cm