Q11 of 107 Page 17

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

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


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