Question

A sector containing an angle of 180o is cut off from a circle of radius 7 cm and folded into a cone. find the curved surface area of the cone (take π = 22/7)

Answer 1

A sector containing an angle of 180° is cut off.  It means a semicircle is cut off.
Radius = R = 7 cm.

Length of the curved arc part = 2 π R * 180°/360° = π R = 22/7 * 7 = 22 cm

After folding it into a cone, the curved part becomes the circumference 
of the base of the cone.
Radius of the base of cone = r cm.
So   2 π r = 22 cm
             r = 3.5 cm

Slanting height s of the cone is the radius of the bigger original circle.
So  s = 7 cm.

CSA = curved surface area = π r s = 22/7 * 3.5 cm * 7 cm
    = 77 cm²

Answer 2

I'm pretty sure the answer is 77m to the power of 2