Question

Ravi wants to make birthday caps for his brothers birthday if each cap having radius 5cm and slant height 14cm how much paper is required for 20 such caps also find its cost if paper costs 2.80 rupees per cm square

Answer 1

Answer:

Complete step by step answer:

As we know, the base radius of the cone is 5 cm.

And the height of the cone is 12 cm.

Now to find the area of the cone we had to find the slant height of the cone.

Now as we know that the formula for slant height of the cone is l=r2+h2−−−−−−√

, where r and h are the base radius and height of the cone.

So, let us find the slant height of the cone (birthday cap).

Slant height = 52+122−−−−−−−√=25+144−−−−−−−√=169−−−√=13

cm.

So, now we can find the curved surface area of one birthday cap.

Curved surface area of one cap = πrl=π×(5)×(13)=65πcm2

.

Now as we know that if the area of one cap is 65πcm2

then the number of caps that can be made in the given sheet of paper = Area of sheet of paperArea of one cap=572065π=572065×227=5720×765×22=400401430=28

Hence, 28 birthday caps can be made from the sheet of the paper.