The area of the curved surface of the cone generated by the sector of a circle radius 6cm and are length 22cm is (\(\pi\) = \(\frac{22}{7}\))
A. 58 sq.cm B. 34 sq.cm C. 132 sq.cm D. 77 sq.cm E. 66 sq.cm
Correct Answer: E
Explanation
Given: length of the arc AOB = 22cm ; L = 6cm Curved surface area of cone = \(\pi\)rl Length of an arc = \(\frac{\theta}{360}\) x 2 \(\pi\)L = 22cm but length of an arc = circumference of the cone = 2\(\pi\) where r is the radius of the cone circle 2\(\pi\)r = 22, r = \(\frac{22}{2\pi}\)r = 11 x \(\frac{7}{22}\) = \(\frac{7}{2}\) curved surface area = \(\pi\)rl = \(\frac{22}{7}\) x \(\frac{7}{2}\) x 6 = 66 sq.cm