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महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता ११ वी

Answer the following: If x + iy = a+iba-ib, prove that x2 + y2 = 1

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प्रश्न

Answer the following:

If x + iy = `("a" + "ib")/("a" - "ib")`, prove that x2 + y2 = 1

बेरीज
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उत्तर

x + iy = `("a" + "ib")/("a" - "ib") = (("a" + "ib")("a" + "ib"))/(("a" - "ib")("a" + "ib"))`

= `("a"^2 + "i"^2"b"^2 + 2"abi")/("a"^2 - "i"^2"b"^2)`

= `(("a"^2 - "b"^2) + 2"abi")/("a"^2 + "b"^2)`   ...[∵ i2 = – 1]

∴ x + iy = `("a"^2 - "b"^2)/("a"^2 + "b"^2) + (2"ab")/("a"^2 + "b"^2)"i"`

Equating real and imaginary parts, we get

x = `("a"^2 - "b"^2)/("a"^2 + "b"^2)` and y = `(2"ab")/("a"^2 + "b"^2)`

∴ x2 + y2 = `(("a"^2 - "b"^2)^2)/("a"^2 + "b"^2)^2 + (4"a"^2"b"^2)/("a"^2 + "b"^2)^2`

= `("a"^4 + "b"^4 - 2"a"^2 "b"^2 + 4"a"^2"b"^2)/("a"^2 + "b"^2)^2`

= `(("a"^2 + "b"^2)^2)/("a"^2 + "b"^2)^2`

∴ x2 + y2 = 1

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पाठ 1: Complex Numbers - Miscellaneous Exercise 1.2 [पृष्ठ २२]

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बालभारती Mathematics and Statistics 2 (Arts and Science) [English] Standard 11 Maharashtra State Board
पाठ 1 Complex Numbers
Miscellaneous Exercise 1.2 | Q II.13 | पृष्ठ २२

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