Question

The slant height (l) of a cone of radius r and height h is

• A. $\sqrt{r^2+h}$
• B. $r^2+h^2$
• C. $\sqrt{r^2+h^2}$
• D. $(r^2+h^2{)}^2$

Answer 1

The correct option is C $\sqrt{r^2+h^2}$


By observing the figure and by applying Pythagoras' theorem in the right-angles triangle whose base is r, height is h and hypotenuse is l(slant height of cone), we get
$l^2=r^2+h^2$
$\Rightarrow l=\sqrt{r^2+h^2}$