Multiple choice general knowledge math & puzzles Which one is incorrect? Area of Square= Length Square Circumference of a circle=Pi (Diameter of circle) Area of Circle=2?r Area of triangle = ½b × h Reveal answer Fill a bubble to check yourself C Correct answer Explanation The formula for the area of a circle is $\pi r^2$. The expression $2\pi r$ represents the circumference of a circle, making this statement incorrect.