Answer:
506.7 cm²
Step-by-step explanation:
The amount of cardboard needed would be the surface area of the cone,
S= pi(r)(l+r) where r is the radius and l is the slant height.
You can find l using the Pythagorean theorem. l²=r²+h² which is l²=6²+20² and you get l = √436.
Plug r and l into the equation: S = 6pi(√436 + 6) = 506.7 cm²
Let me know if you have any questions about my steps!
