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Mathematics 8 Online
OpenStudy (anonymous):

Find the surface area of the cone to the nearest whole unit.

OpenStudy (anonymous):

sammixboo (sammixboo):

Do you know the formula to find the SA (Surface Area) of a cone?

OpenStudy (anonymous):

umm.. SA = pi-r^2 + pi-rl

OpenStudy (anonymous):

(technically theres no dash between pi and r but just so it's not confusing)

sammixboo (sammixboo):

Right! pi = 3.14 so we can plug that in SA = 3.14r^2 + 3.14rl

sammixboo (sammixboo):

R = Radius L = Slant Height Can you tell me the radius (half of diameter) and slant height of this cone is?

OpenStudy (anonymous):

4 and 7?

sammixboo (sammixboo):

Right! So R = 4 and L = 7 Plug it is SA = 3.14*4^2 + 3,14*4*7

OpenStudy (anonymous):

50.24 + 87.92 = 138.16 so 138. Thank you so much!

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