A toy is in the form of a hemisphere surmounted by a right circular cone of the same base radius as that of the hemisphere. If the radius of the base of the cone is 21 cm and its volume is 2/3 of the volume of the hemisphere, calculate the height of the cone and the surface area of the toy. 
Radius of base = 21cm and its volume = 2/3 × volume of the hemisphere
Hence surface area of the toy = Surface area of the cone + Surface area of hemisphere
= π r (
) + 2 π r2
= π (21)[35 + 2 × 21]
= 5082 cm2
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