Question
Wed February 27, 2013 By:
 

find the curved surface area of cone using the given figure. given base diameter 12 cm and the angle at the conical vertices is 120

Expert Reply
Thu February 28, 2013
Radius of the cone = 12/2 cm = 6 cm
Apex angle = 120
Slant height(l) = radius/sin(120/2) (Considering trignometry in the cone triangle)
l = 6/sin60
l = 12/sqrt(3)
l = 4*sqrt(3)
 
Curved surface area of a cone = pi*r*l = pi * 6*4*sqrt(3) = 130.53 cm2
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