Chemegate

GATE 2026 Chemical Engineering, Q41 · Mathematics

The correct answer is D, 6π.

Question

Consider the following curve in polar coordinates: r = 2 2 sin θ.θ. Which one of the following is the area enclosed by the curve for 0θ2π?0 \leq θ \leq 2π?

  • A. 3π
  • B. 4π
  • C. 5π
  • D. 6π

Official answer: 6π

Why

GATE 2026 official key: (D). Area enclosed by a polar curve is A =½02πr2dθ.= ½\int ₀^{2π} r² dθ. With r=2(1sinθ),r2=4(12sinθ+sin2θ);r=2(1−sinθ), r²=4(1−2sinθ+sin²θ); since sinθdθ=0\int sinθdθ=0 and sin2θdθ=π\int sin²θdθ=π over a full period, A =2(2π0+π)=6π.= 2(2π−0+π) = 6π.

Explanation cross-checked for consistency. Final answer matches the official IIT answer key.