Shadow area = the sum of three sector areas with a radius of 8cm and a central angle of 60.
3×(8? ×3. 14×60/360)
=200.96cm?
The perimeter of the middle part of the triangle:
The arc length of three sectors with a central angle of 60 is also equal to half the circumference of a circle with a radius of 8cm.
8× 2× 3.14÷ 2 = 25.12cm