The base of a conical tent is of area 616 sq. cm. A 48 cm long vertical pole is placed at its centre so that it touches the roof of the tent. How much canvas is needed to make the tent if the base is also covered with canvas?
Here, we need to calculate the total surface area of the cone.
Total surface area of the cone = πr(l+r)
=πrl+πr2
where πr2 is the area of the base of the cone.
Given: πr2=616 cm2
⇒227×r2=616
⇒r2=616×722=196 cm2
⇒ r = 14 cm
Also, h = 48 cm
Now, l=√h2+r2
=√482+142
=√2304+196
=√2500=50 cm
So, T. S. A of conical tent =πrl+πr2
=227×14×50+616
=2816 cm2