Image caption, ...you've done it! The sectors rearranged into the rectangle show the area of the curved surface of the cone = π × radius × slant length.

text{area of base} = \pi \times 8^{2} = 64 \pi\) \(\text{area of top} = \pi \times 4^{2} = 16 \pi\) The net of a cone is a sector of a circle with a radius of 15cm. The angle in the sector is 114°.