Note: The animation is continued in the pictures below.

12 T- 6 -18 -12 -6 12 18 -6 -12 -18 In the animation above you can see a curve that is traced by a point on the perimeter of a circle rolling around another circle of the same radius. The parametric presentation of this curve is r(1) = = 6(2 cost - cos 21) 6(2 sin t - sin 21) ] I E [0, 2x), Find the arc length of the curve. These trigonometric identities may be useful: cos(a - ) = cos a cos B + sin a sin B 1 - cos 2t = 2 sin t Arc length:\f18 12 6 -18 -12 -6 12 18 -6. -12 -18 D18 12 6 -18 -12 -6 12 18 -6 -1P -18