Circle Area — sectors into a parallelogram

Cut a circle into equal sectors, rearrange, and read off A = πr²

Sectors

16 equal sectors

Even counts only, so the two rows of the parallelogram hold exactly half the circle each.

Circle → parallelogram 0%

Top row → half circle 0%

Length ℓ

Width w

Highlight the half circumference Sector outlines Original circle outline Exact measurements

A = ℓ · w ℓ = 12C ℓ = 12(2πr) = πr w = r A = (πr)(r) = πr²