Since the radius of the semi circle is 10 cm then the diameter is 20 cm, when folded, its circumference is now 20, given the circumference find the radius of the cone. i guess 
Volume = 1/3 πr2 (l2﹣r2)1/2
circumference = 20 cm = πD
D=6.363636364
 Radius = 6.363636364/2 = 3.181818182
l = 10
vol = 100.51cm3
curved s.a = πrl
=99.96cm2
 
        
             
        
        
        
12+8y you have to do like terms and the distributive property of 2(y+1)
        
             
        
        
        
Answer:
V = ⅓πr²h = ⅓(3.14)(7.5/2)²(4.25) = 62.5546875 ≈ 62.6 ft³
Step-by-step explanation: