Mathematics - Geometry - Circles - Area of circles - Circle Area Formula

5 steps: (1) Area of a circle = πr². (2) Example: r=6cm. A=π(6²)=36π≈113.1 cm². (3) If given diameter: first find radius (d/2), then use formula. d=10 → r=5 → A=25π≈78.5. (4) Working backwards: A=50.24cm², find r. r²=A/π=50.24/3.14=16, r=4cm. (5) Common mistake: squaring the diameter instead of radi