1. The perimeter of the square is 32 units, means each side is 32/4=8 units.
rotating the square about line k forms a cylinder with base radius equal to 8 units, and height equal to 8 units. (check the first picture)
the circumference of the base is C=2πR=16π units=16*3.14 units = 50.24 units.
Answer: a cylinder with a circumference of about 50 units
2.
Rotating the equilateral triangle around line a, produces a cone with base radius equal to half of one side of the triangle, that is r=10mm.
(check picture 2)
The circumference is C = 2πr=C = 2*3.14*10=62.8 mm
Answer: a cone with a base circumference of about 63 mm
