Question

from a circular sheet of radius 10 cm , a disc of radius 3 cm is cut out and the portion of the sheet left behind is painted at the rate of rs 0.35 per cm square .find the cost of painting the sheet

Answer 1

Answer:

Step-by-step explanation:

Formula used:

$Area\: of \:a\: circle \:of\: radius \:r \:is\:\pi{r}^2$

$Area\: of \:the\: circular\: sheet=\pi{(10)}^2=100\pi \:square \:cm$

$Area \:of\: the \:circular \:disc=\pi{(3)}^2=9\pi square cm$

$Area\: of \:the \:portion\: left=100\pi-9\pi=91\pi\:square\: cm.$

Cost of painting for square cm is Rs.0.35$Cost \:of \:painting \:for \:91\pi\:square \:cm\: is \:91\pi(0.35)$

=91×(22/7)×0.35

=13×22×0.35

=286×0.35

=Rs.100.10

Answer 2

Answer: Rs 100.10

Step-by-step explanation:

The radius of circular sheet is 10 cm

We have to find Area of outer sheet

       Area of outer sheet = πr²

                                           = 22 / 7 × (10)²

                                          = 22/7 × 100

`                                          = 314.28 cm²

Now we have to find out  the Area of cut out sheet

   radius of cut out sheet = 3 cm

Area of cut out sheet =  πr²

                                     =22/7 × (3)²

                                     = 22/7 × 9

                                       = 28.28 cm²

Area of remaining sheet = area of outer sheet - area of cut out sheet

                                          = 314.28 - 28.28

                                           = 286 cm²

Cost of painting per cm = Rs. 0.35

Cost of painting 286 cm =  286 × 0.35

                                            =Rs . 100.10

Hence the cost is Rs. 100.10