Question

A solid consists of a conical part, a cylindrical part and a hemispherical part. All the parts have the same diameter of 12cm. The height of the cylindrical part is 15cm and the slanting height of the conical part is 10 cm. (Take π = 3.142).  
Calculate the:  

1. height of the solid; 
2. surface area of the solid, correct to 1 decimal place,
3. volume of the solid, correct to 1 decimal place. 

Answer 1

1. Total height =8+15+6
                =29 cm
2. SA= πrl + 2πr² + 2πrh
   = 3.142× 6×10 + 2×3.142×62 + 2×3.142×6×15
   =188.52+565.56+226.22
   = 980.304
    ≈ 980.3 sq.cm
3. V=1/3xAh + πr²h + ²/₃πr³
     = 1/3 × 3.142×36×8 + 3.142×36×15 + 2/3 × 3.142 × 216
     =2450.76 cubic cm
     ≈2450.8cm³