Question

Surface area of a cone is $188.4$ sq. cm and its slant height is $10$cm. Find its perpendicular height $\left(\pi =3.14\right)$

Answer 1

Surface area of a cone$=188.4sq.cm$

$\Rightarrow \pi rl=188.4sq.cm$

$\Rightarrow r=\frac{188.4}{3.14\times 10}=6cm$

Perpendicular distance$=h^2=l^2-r^2$

$\Rightarrow h^2={10}^2-6^2=100-36=64$

$\therefore h=8cm$

Hence the Perpendicular distance is $8cm$