Given radius of cone = radius of hemisphere

Radius (r) = 21cm

Given that volume of cone =2/3 Volume of hemisphere

l = √(h^{2} + r^{2})

l = √(28^{2} + 21^{2})

l = √(784 + 441)

l = √(1225)

l = 35cm

S_{1} = π(21)(35) cm^{2}

S_{1 }= 2310 cm^{2}

Curved surface area off hemisphere = 2πr^{2}

S_{2}= 2 x π(21)^{2}

S_{2} = 2772 cm^{2}

Total surface area (S) = S_{1} +S_{2}

= 2310 + 2772 = 5082 cm^{2}

Curved surface area of toy = 5082 cm^{2}