A metallic right circular cone 20 cm high and whose vertical angle is 90° is cut into two parts at the middle point of its axis by a plane parallel to the base. If the frustum so obtained be drawn into a wire of diameter (1/16) cm, find the length of the wire

Question

A metallic right circular cone 20 cm high and whose vertical angle is 90&#xB0; is cut into two parts at the middle point of its axis by a plane parallel to the base. If the frustum so obtained be drawn into a wire of diameter (1/16) cm, find the length of the wire

Philoid · Accepted Answer

let ABC be the given cone.

Here, height of the metallic cone AO = 20cm

cone is cut nto two pieces at the middle point of the axis

hence, height of the frustum cone AD = 10cm

Since angle A is right angled, so ∠B and ∠C both = 45°

From triangle ADE,

⇒ r'=10cm

Similarly, from triangle AOB,

⇒ r''=20cm