The equilateral triangle shown is rotated about line a. each side of the triangle measures 20 mm. an equilateral triangle is sho
wn. line of rotation a goes through one point and the midpoint of the opposite side. what shape is created by the rotation and what is the approximate circumference of the base? circumference of a circle: c = 2πr a cylinder with a circumference of about 63 mm a cylinder with a circumference of about 126 mm a cone with a base circumference of about 63 mm a cone with a base circumference of about 126 mm