If |z2+iz1|=|z1|+|z2| and |z1|=3 and |z2|=4, then area of △ABC, if affixes of A,B and C are z1,z2 and [z2−iz11−i] respectively, is,
A
52 sq. units
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B
0 sq. unit
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C
252 sq. units
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D
254 sq. units
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Solution
The correct option is D254 sq. units |z2+iz1|=|z1|+|z2|⇒|z2+iz1|=|z2|+|iz1| ⇒iz1,0+i0 and z2 are collinear ⇒arg(iz1)=arg(z2) ⇒arg(z2)−arg(z1)=π2
Let, z3=z2−iz11−i ⇒(1−i)z3=z2−iz1 ⇒z2−z3=i(z1−z3) ∴∠ACB=π2 and |z1−z3|=|z2−z3| ⇒AC=BC ∵AB2=AC2+BC2 ⇒AC=5√2(∵AB=5) Therefore area of △ABC =(12)AC×BC=254 sq.unit