Question

a soli wooden cone of diameter 14 cm and vertical height 24cm vertically cut into two equal halves one-half is to be covered by colourful paper at the rate of Rs 7 per square find the total cost of the paper required​

Answer 1

Cost of paper required = Rs. 3640

Step-by-step explanation:

Given,

Diameter = 14 cm   =$2\times Radius$

Radius = 7 cm

Height = 24 cm

slant height = $\sqrt(24^2 + 7^2)$

                   = $\sqrt(625)$

                   = 25 cm

Cost per square cm = Rs.7

Total Surface Area of cone = $\pi r(r + l)$

                                              = $\frac{22}{7} 7 (7 + 25)$

                                             =$704\ cm^2$

Half of total surface area = $352\ cm^2$

Since the cone is cut into two halves vertically

Area to be covered with coloured paper = Half of total surface area + Area of triangle on one side

Area of triangle =$\frac{1}{2}\times base\times height$

                          = $\frac{1}{2}\times 14\times 24$ [diameter will be considered as base of triangle]

                          = $168\ cm^2$

Area to be covered with coloured paper = 352 + 168

                                                                    =  $520\ cm^2$

Cost of paper required =$\textrm{Area to be covered with paper} \times \textrm{Cost per square cm}$

                                       = 520 × 7

                                       = Rs. 3640.