<PRE><B>Question 1179312</B>
Diameter of cone=10cm
Radius of cone r=Diameter/2=10/2=5cm
Total surface area=285 cm
Surface area of cone=pi*r(r+l) where l is the slant height.
Plugging in the values we get,
pi*5(5+l)=285
5+l=9.0718
l=4.0718cm
The slant height is l=4.0718 cm
Answer=4.0718 cm</PRE>