Question

find the curved surface area of a cone of radius 7 cm and height 24 cm with hemispherical. Find the cost of painting at rate of 2 rs

Answer 1

Solution:

Formula used:

1. Curved surface area of a cone is $\pi\:r\:l$

2. Cured surface area of a hemi sphere is

$2\pi\;r^2$

Given:

radius, r=7 m

height, h=24m

we know that

$l^2=h^2+r^2\\l^2=24^2+7^2\\l^2=576+49\\l^2=625l=\sqrt{625}$

slant height, l=25 m

Total area required

=CSA of conical portion+CSA of hemispherical portion

$=\pi\:rl+2\pi\:r^2$

$=(\frac{22}{7}.7.25)+(2.\frac{22}{7}.7^2)$

=550+38

=588 square meter

cost of painting per square meter is Rs,2

cost of painting for 588 square meter is

588X2

=Rs.1176