मराठी
महाराष्ट्र राज्य शिक्षण मंडळएचएससी विज्ञान (सामान्य) इयत्ता ११ वी

Find real values of θ for which (4+3isinθ1-2isinθ) is purely real.

Advertisements
Advertisements

प्रश्न

Find real values of θ for which `((4 + 3"i" sintheta)/(1 - 2"i" sin theta))` is purely real.

बेरीज
Advertisements

उत्तर

Let z = `(4 + 3"i" sintheta)/(1 - 2"i" sintheta)`

= `(4 + 3"i" sintheta)/(1 - 2"i" sintheta) xx (1 + 2"i" sintheta)/(1 + 2"i" sintheta)`

= `(4 + 8"i" sintheta + 3"i" sintheta + 6"i"^2 sin^2theta)/(1 - 4"i"^2 sin^2theta)`

= `(4 + (11 sintheta)"i" - 6 sin^2theta)/(1 + 4 sin^2theta)`    ...[∵ i2 = – 1]

= `((4 - 6 sin^2theta) + (11 sintheta)"i")/(1 + 4 sin^2theta)`

∴ z = `((4 - 6 sin^2theta)/(1 + 4 sin^2theta)) + ((11 sintheta)/(1 + 4 sin^2theta))"i"`

Since z is purely real, Im(z) = 0

∴ `(11 sintheta)/(1 + 4 sin^2theta)` = 0

∴ sin θ = 0 = sin nπ, where n ∈ Z

∴ θ = nπ, where n ∈ Z.

shaalaa.com
  या प्रश्नात किंवा उत्तरात काही त्रुटी आहे का?
पाठ 1: Complex Numbers - Exercise 1.3 [पृष्ठ १५]

संबंधित प्रश्‍न

Find the modulus and amplitude of the following complex numbers.

7 − 5i


Find the modulus and amplitude of the following complex numbers.

−8 + 15i


Find the modulus and amplitude of the following complex numbers.

1 + i


Find the modulus and amplitude of the following complex numbers.

`1 + "i"sqrt(3)`


If z = 3 + 5i then represent the `"z", bar("z"), - "z", bar(-"z")` in Argand's diagram


Express the following complex numbers in polar form and exponential form: 

`-1 + sqrt(3)"i"`


Express the following complex numbers in polar form and exponential form:

− i


Express the following numbers in the form x + iy: 

`sqrt(3)(cos  pi/6 + "i" sin  pi/6)`


Express the following numbers in the form x + iy:

`"e"^(pi/3"i")`


Express the following numbers in the form x + iy:

`"e"^((5pi)/6"i")`


Find the modulus and argument of the complex number `(1 + 2"i")/(1 - 3"i")`


Convert the complex number z = `("i" - 1)/(cos  pi/3 + "i" sin  pi/3)` in the polar form


For z = 2 + 3i verify the following:

`bar((bar"z"))` = z


For z = 2 + 3i verify the following:

`"z"bar("z")` = |z|2


For z = 2 + 3i verify the following:

`"z" - bar"z"` = 6i


z1 = 1 + i, z2 = 2 − 3i. Verify the following : 

`bar("z"_1 - "z"_2) = bar("z"_1) - bar("z"_2)`


z1 = 1 + i, z2 = 2 − 3i. Verify the following :

`bar("z"_1."z"_2) = bar("z"_1).bar("z"_2)`


z1 = 1 + i, z2 = 2 − 3i. Verify the following :

`bar(("z"_1/"z"_2))=bar("z"_1)/bar("z"_2)`


Select the correct answer from the given alternatives:

If `-1 + sqrt(3)"i"` = re , then θ = ................. 


Select the correct answer from the given alternatives:

If z = x + iy and |z − zi| = 1 then


Answer the following:

Find the modulus and argument of a complex number and express it in the polar form.

6 − i


Answer the following:

Find the modulus and argument of a complex number and express it in the polar form.

`(1 + sqrt(3)"i")/2`


Answer the following:

Find the modulus and argument of a complex number and express it in the polar form.

− 3i


Answer the following:

Convert the complex numbers in polar form and also in exponential form.

z = `-6 + sqrt(2)"i"`


Convert the complex numbers in polar form and also in exponential form.

`(-3)/2 + (3sqrt(3))/2"i"`


The polar coordinates of the point whose cartesian coordinates are (−2, −2), are given by ____________.


The modulus and amplitude of 4 + 3i are ______


If z = `5i ((-3)/5 i)`, then z is equal to 3 + bi. The value of ‘b’ is ______.


If A, B, C are three points in argand plane representing the complex numbers z1, z2 and z3 such that, z1 = `(λz_2 + z_3)/(λ + 1)`, where λ ∈ R, then find the distance of point A from the line joining points B and C.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×