Problem: the slant height of a right circular cone is 10 m and its height is 8 m . find the area of its curved surface . 
Options: ['a ) 30 pi m ^ 2', 'b ) 40 pi m ^ 2', 'c ) 60 pi m ^ 2', 'd ) 80 pi m ^ 2', 'e ) 100 pi m ^ 2']
c