really cant do this one (1 Viewer)

[c0okies]

A cone is made by joining together the radii of the sector of a circle of radius 16cm. The radius of the base of the cone is 4cm. Find the angle at the centre of the sector and the curved surface area of the cone.

Thanks ahead for any help;

 

[pLuvia]

n is pi

The arc of the sector of the circle is circumference of the cone which would be 8n

Using the formula l=r@ where l=8n, r=16 .: @=3n/4 = 135^o

Surface area of the curved SA of the cone = nSr
= nx16x4 = 201.06cm²