Surface Area of a Cone
POINT
A cone’s curved surface unfolds into a sector. Its arc length equals the circumference of the base. The curved area is πrl; add the base area πr² for total surface area.
EXAMPLE
For the cone with radius 3 cm and slant height 8 cm: (1) Find the central angle of its sector. (2) Find its total surface area.
Practice
Find the total surface area of each cone.
01
Radius: 4 cm; Slant height: 9 cm
\(52\pi\,\mathrm{cm}^2\)
02
Radius: 5 cm; Slant height: 12 cm
\(85\pi\,\mathrm{cm}^2\)
03
Radius: 6 cm; Slant height: 10 cm
\(96\pi\,\mathrm{cm}^2\)
04
Radius: 7 cm; Slant height: 15 cm
\(154\pi\,\mathrm{cm}^2\)
Have a question? Ask in the video comments! ✏️