Question

Find the surface area of a frustum of a given cone: (Use $\pi$ $=3.14$)

• A. $1,398.26$ in${}^2$
• B. $1,498.26$ in${}^2$
• C. $1,298.26$ in${}^2$
• D. $1,598.26$ in${}^2$

Answer 1

Answer: (D)

$1,598.26$ in${}^2$

Surface area of a frustum of cone $=\pi (r+R)s+\pi r^2+\pi R^2$

$R=12\text{in},r=5\text{in},s=20\text{in}$

$=\pi (5+12)20+\pi (5{)}^2+\pi {12}^2$

$=340\times 3.14+25\times 3.14+1443.14$

$=1,067.6+78.5+452.16$

$=1,598.26{\text{in}}^2$