Paragraph: Let $S=S_{1} \cap S_{2} \cap S_{3}$, where $S_{1}=\{z \in \mathbb{C}:|z| 0\right\}$ and…

Paragraph: Let $S=S_{1} \cap S_{2} \cap S_{3}$, where $S_{1}=\{z \in \mathbb{C}:|z|<4\}, \quad S_{2}=\left\{z \in \mathbb{C}: \operatorname{Im}\left[\frac{z-1+\sqrt{3} i}{1-\sqrt{3} i}\right]>0\right\}$ and $S_{3}=\{z \in \mathbb{C}: \operatorname{Re} z>0\}$.
Question: Area of $S=$
  1. 1 0 π 3
  2. 2 0 π 3
  3. 1 6 π 3
  4. 3 2 π 3

Solution

S1 : x2 + y2 < 16
S 2  :  z - 1 + 3 i 1 - i 3 = x - 1 + y + 3 1 - 3 i
= x - 1 + y + 3   1 + 3  i 1 + 3


S 2  :  x - 1 3 + y + 3 9 > 0
S 2  :  3 x + y > 0  &  S 3  :  x > 0
A = 1 2 r 2 θ = 1 2 × 1 6 × 5 π 6 = 4 0 π 6 = 2 0 π 3

Asked in: JEE Advanced 2013 (Paper 2)

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