CBSE BoardEnglish MediumSTD 11 ScienceMathsComplex Numbers and Quadratic Equations1 Mark
MCQ
Choose the correct answer. If $a + ib = c + id,$ then:
A
$ a^2+c^2=0 $
B
$ b^2+c^2=0 $
C
$ b^2+d^2=0 $
✓
$ a^2+b^2=c^2+d^2 $
✓
Answer
Correct option: D.
$ a^2+b^2=c^2+d^2 $
Given that $\text{a}+\text{ib}=\text{c}+\text{id}$
$\Rightarrow|\text{a}+\text{ib}|=|\text{c}+\text{id}|$
$\Rightarrow\sqrt{\text{a}^2+\text{b}^2}=\sqrt{\text{c}^2+\text{d}^2}$
Squaring both sides, we get $ a^2+b^2=c^2+d^2 $
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