a. A(t)=A(r(t))=π⋅(6−5t2+1)2A(t)=A(r(t))=\pi \cdot {\left(6−\frac{5}{t^2+1}\right)}^2 A(t)=A(r(t))=π⋅(6−t2+15)2 b. Exacto: 121π4\frac{121\pi}{4}4121π; aproximadamente 95 cm2cm^2cm2 c. C(t)=C(r(t))=2π(6−5t2+1)C(t)=C(r(t))=2\pi\left(6−\frac{5}{t^2+1}\right)C(t)=C(r(t))=2π(6−t2+15) d. Exacto: 11π11\pi11π; aproximadamente 35 cm