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Complex Numbers Model Question Paper 1

12th Standard

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Maths

Time : 01:00:00 Hrs
Total Marks : 50
    5 x 1 = 5
  1.  The value of \(\sum_{n=1}^{13}\left(i^{n}+i^{n-1}\right)\) is

    (a)

    1+ i

    (b)

    i

    (c)

    1

    (d)

    0

  2. If |z - 2 + i | ≤ 2, then the greatest value of |z| is

    (a)

    \(\sqrt { 3 } -2\)

    (b)

    \(\sqrt { 3 } +2\)

    (c)

    \(\sqrt { 5 } -2\)

    (d)

    \(\sqrt { 5 } +2\)

  3. If |z1| = 1, |z2| = 2, |z3| = 3 and |9z1z+ 4z1z+ z2z3| = 12, then the value of |z1+z2+z3| is 

    (a)

    1

    (b)

    2

    (c)

    3

    (d)

    4

  4. If z = cos\(\frac { \pi }{ 4 } \) + i sin\(\frac { \pi }{ 6 } \), then ______

    (a)

    |z| = 1, arg(z) =\(\frac { \pi }{ 4 } \)

    (b)

    |z| = 1, arg(z) = \(\frac { \pi }{ 6 } \)

    (c)

    |z| = \(\frac { \sqrt { 3 } }{ 2 } \), arg(z) = \(\frac { 5\pi }{ 24 } \)

    (d)

    |z| = \(\frac { \sqrt { 3 } }{ 2 } \), arg (z) = tan-1\(\left( \frac { 1 }{ \sqrt { 2 } } \right) \)

  5. If z = \(\frac { 1 }{ 1-cos\theta -isin\theta } \), the Re(z) = ___________

    (a)

    0

    (b)

    \(\frac{1}{2}\)

    (c)

    cot\(\frac { \theta }{ 2 } \)

    (d)

    \(\frac{1}{2}\) cot\(\frac { \theta }{ 2 } \)

  6. 5 x 2 = 10
  7. Find the square roots of 4+3i

  8. Obtain the Cartesian form of the locus of z = x + iy in each of the following cases:
    \(\left[ Re\left( iz \right) \right] ^{ 2 }=3\)

  9. If (cosθ + i sinθ)2 = x + iy, then show that x2+y2 =1

  10. Find the argument of -2

  11. Find the values of the real number x and y if 3x + (2x - 3y) i = 6 + 3i9.

  12. 5 x 3 = 15
  13. If z= 3, z= -7i, and z= 5 + 4i, show that z1(z+ z3) = zz+ zz3

  14. If z1= 2 + 5i, z= -3 - 4i, and z= 1 + i, find the additive and multiplicate inverse of z1, z2 and z3

  15. Find the principal value of -2i.

  16. Find the locus of z if |3z - 5| = 3 |z + 1| where z = x + iy.

  17. If \(\frac { (a+i)^{ 2 } }{ 2a-i } \) = p + iq, show that p2+q2\(\frac { ({ a }^{ 2 }+i)^{ 2 } }{ 4a^{ 2 }+1 } \).

  18. 4 x 5 = 20
  19. If z = x + iy and arg \(\left( \frac { z-i }{ z+2 } \right) =\frac { \pi }{ 4 } \), then show that x+ y+ 3x - 3y + 2 = 0

  20. Show that \(\left( \frac { \sqrt { 3 } }{ 2 } +\frac { i }{ 2 } \right) ^{ 5 }+\left( \frac { \sqrt { 3 } }{ 2 } -\frac { i }{ 2 } \right) ^{ 5 }=-\sqrt { 3 } \)

  21. Verify that arg(1+i) + arg(1-i) = arg[(1+i) (1-i)]

  22. Find all the roots \((2-2i)^{ \frac { 1 }{ 3 } }\) and also find the product of its roots.

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