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QJEEM21Ma96e2: JEE Main 2021 Mathematics - Class 11 JEEM21Ma96e2 Solution: Let a complex number be w = 1 i. Let another complex number z…

Let a complex number be w = 1 −- 3{\sqrt 3 } i. Let another complex number z be such that |zw| = 1 and arg(z) −- arg(w) = π2{\pi \over 2} . Then the area of the triangle with vertices origin, z and w is equal to :

Multiple Choice Options

  • A 4
  • B 14{1 \over 4}
  • C 2
  • D 12{1 \over 2}

Step-by-Step Verified Solution

JEE Main 2021 (Online) 18th March Evening Shift Mathematics - Complex Numbers Question 101 English Explanation
Given, w = 1 −- 3\sqrt 3 i

⇒∣w∣=(1)2+(−3)2=2\Rightarrow |w| = \sqrt {{{(1)}^2} + {{( - \sqrt 3 )}^2}} = 2

Also, given | zw | = 1

⇒\Rightarrow | z | | w | = 1 (using property)

⇒\Rightarrow | z | = 12{1 \over 2}

Also, arg(z) −- arg(w) = π2{{\pi {} } \over 2}

∴\therefore Angle between two complex number z and w is π2{{\pi {} } \over 2} .

∴\therefore ∠zow=π2\angle zow = {{\pi {} } \over 2}

∴\therefore Δ\Delta zow is a right angle triangle with base ow=2ow = 2 and height oz=12oz = {1 \over 2}

∴\therefore Area = 12×2×12=12{1 \over 2} \times 2 \times {1 \over 2} = {1 \over 2}

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