ARC LENGTH AND SURFACE AREA

Question

Find the area of the surface obtained by rotating the curve y=cos(2x),0≤x≤(𝜋/6),about the 𝑥x-axis.

Answer 1

y' = - 2sin(2x).

Surface area S = 2π∫₀^π/6cos(2x)√1 + 4sin²(2x)dx = 3.755