a right circular cone of height 4 cm has a curved surface area 47.1 cm ^2 .find its volume

Question

37.68 cm^3 Answer it urgently with stepwise calculation sir please humble request 

Answer 1

A=(pi)r(r+(sqrt(h^2+r^2)) 47.1/pi=14.99 which I'll call 15 15(pi)=(pi)r(r+sqrt(16+r^2)) divide both sides by pi 15=r(r+sqrt(16+r^2) 15=r^2+rsqrt(16+r^2) 15-r^2=rsqrt(16+r^2) square both sides 225-30r^2+r^4=r^2(16+r^2) 225-30r^2+r^4=16r^2+r^4 subtract r^4 from both sides 225-30r^2=16r^2 16r^2+30r^2=225 46r^2=225 r^2=225/46 r^2=4.89 take the square root of both sides r=2.21cm V=(pi)r^2h/3 V=(3.14159)(2.21^2)(4)/3 V=(3.14159)(4.89)(4)/3 V=(3.14159)(1.63)(4) (4.89/3=1.63) V=(3.14159)(6.52) V=20.483167 cubic centimeters