Question 980523


The slant height of the cone is equal to the radius of the original circular piece of paper,  i.e  20 cm.  It is obvious.


Now, &nbsp;let &nbsp;<B>x</B>&nbsp; be the radius of the base of the cone. 

Then the length of the circle at the base of the cone is &nbsp;2*pi*r. &nbsp;From the other side, &nbsp;it is equal to the length of the half-circle of the radius &nbsp;20 cm.


Thus we have the equation


{{{2*pi*x}}} = {{{2*pi*20/2}}}.


Hence, &nbsp;x = 10 cm.


<B>Answer</B>. &nbsp;The slant height of the cone is &nbsp;20 cm. &nbsp;The radius of the base of the cone is &nbsp;10 cm.