Question

If hieght and radius of a cone are h and r respectively and it is given that hieght of the cone is same as diameter of the base
then find the slant height

Answer 1

$Slant Height (l) = \sqrt{Height(h)^2+Radius(r)^2}$

Now according to question h = 2r

Therfore $l = \sqrt{(2r)^2+r^2}$
$l = r* \sqrt{5}$

Answer 2

(slant height) l² = r² + h²
                      l = √r² + h²
 given, 
          diameter = height
           or,      2r = h
  l = r² + h²
or,      l = r² +(2r)²                              [because h=2r]
          l = r² + 4r²
          l = 5r²                     or             l = r×√5
therefore, slant height of the cone is 5r²