Question

Find the curved surface area and total surface area of a cone whose
Base diameter $=28cm$, slant height $=50cm$
Base diameter $=70cm$, height $8.4cm$

• A. $2200c{m}^2,2815c{m}^2;10010c{m}^2,13860c{m}^2$
• B. $2200c{m}^2,2816c{m}^2;10110c{m}^2,13860c{m}^2$
• C. $2200c{m}^2,2816c{m}^2;10010c{m}^2,13860c{m}^2$
• D. $2200c{m}^2,2816c{m}^2;10010c{m}^2,13660c{m}^2$

Answer 1

The correct option is C $2200c{m}^2,2816c{m}^2;10010c{m}^2,13860c{m}^2$

$radius=14$, slant height $=50$
Curved surface area of cone$=\pi \left(14\right)\left(50\right)=2200c{m}^2$
Total surface area of cone$\pi r(r+l)=\pi \left(14\right)(14+50)=2816c{m}^2$
radius=35,height =8.4 dm=84 cm,slant height$=\sqrt{r^2+h^2}=91cm$
Curved surface area of cone$=\pi \left(35\right)\left(91\right)=10010c{m}^2$
Total surface area of cone $=\pi r(r+l)c{m}^2=\pi \left(35\right)(35+91)=13860c{m}^2$