The perimeters of a circle, a square and an equilateral triangle are equal. Which one of the following statements is true?
A. The circle has the largest area
B. The square has the largest area
C. The equilateral triangle has the largest area
D. All the three shapes have the same area
GATE 2018 · General Aptitude · Geometry · easy
Answer: The circle has the largest area — Option A
Area of circle in terms of P: Coefficient of P^2 is 1/(4 pi) ≈ 1/12.566 ≈ 0.0796
Area of square in terms of P: Coefficient of P^2 is 1/16 = 0.0625
Area of equilateral triangle in terms of P: Coefficient of P^2 is sqrt(3)/36 ≈ 1.732/36 ≈ 0.0481
Compare coefficients: A_c > A_s > A_t for any fixed P