Verified Solution • 2025–26 Session moderate

QJEEM24Mae193: JEE Main 2024 Mathematics - Class 11 JEEM24Mae193 Solution: Let and . Then the area of the region is :

Let S1={z∈C:∣z∣≤5},S2={z∈C:Im⁡(z+1−3i1−3i)≥0}S_1=\{z \in \mathbf{C}:|z| \leq 5\}, S_2=\left\{z \in \mathbf{C}: \operatorname{Im}\left(\frac{z+1-\sqrt{3} i}{1-\sqrt{3} i}\right) \geq 0\right\} and S3={z∈C:Re⁡(z)≥0}S_3=\{z \in \mathbf{C}: \operatorname{Re}(z) \geq 0\} . Then the area of the region S1∩S2∩S3S_1 \cap S_2 \cap S_3 is :

Multiple Choice Options

  • A 125π24\frac{125 \pi}{24}
  • B 125π6\frac{125 \pi}{6}
  • C 125π12\frac{125 \pi}{12}
  • D 125π4\frac{125 \pi}{4}

Step-by-Step Verified Solution

S1={z∈C:∣z∣≤5}S_1=\{z \in C:|z| \leq 5\}

JEE Main 2024 (Online) 5th April Evening Shift Mathematics - Complex Numbers Question 12 English Explanation 1

S2=Im⁡(z+1−3i1−3i)≥0S_2=\operatorname{Im}\left(\frac{z+1-\sqrt{3} i}{1-\sqrt{3} i}\right) \geq 0

Take z=x+iyz=x+i y

=x+iy+1−3i1−3i×1+3i1+3i=\frac{x+i y+1-\sqrt{3} i}{1-\sqrt{3} i} \times \frac{1+\sqrt{3} i}{1+\sqrt{3} i}

=amp;x+iy+1−3i+3ix−3y+3i+31+3amp;=y+3x≥0S3=amp;x≥0\begin{aligned}= & \frac{x+i y+1-\sqrt{3} i+\sqrt{3} i x-\sqrt{3} y+\sqrt{3} i+3}{1+3} \\& =y+\sqrt{3} x \geq 0 \\S_3= & x \geq 0\end{aligned}

JEE Main 2024 (Online) 5th April Evening Shift Mathematics - Complex Numbers Question 12 English Explanation 2

amp;y+3x=0amp;y=−3xamp; Slope =−3amp;90+θ=120∘amp;θ=30∘amp;90−θ=60∘\begin{aligned}& y+\sqrt{3} x=0 \\& y=-\sqrt{3} x \\& \text { Slope }=-\sqrt{3} \\& 90+\theta=120^{\circ} \\& \theta=30^{\circ} \\& 90-\theta=60^{\circ}\end{aligned}

In first quadrant we have angle π2\frac{\pi}{2}

so, total angle 90∘+60∘=150∘90^{\circ}+60^{\circ}=150^{\circ}

So, area πr22π×5π6=125π12\frac{\pi r^2}{2 \pi} \times \frac{5 \pi}{6}=\frac{125 \pi}{12}

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