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The amplitude of sin (pi)/(5) +i(1-cos""...

The amplitude of sin `(pi)/(5) +i(1-cos"" (pi)/(5)) ` is

A

`(2pi)/5`

B

`pi/15`

C

`pi/10`

D

`pi/5`

Text Solution

Verified by Experts

The correct Answer is:
C
We have,
`z=sinpi/5+i(1-cospi/5)=2sinpi/10cospi/10+2isin^(2)pi/10`
`rArr z=2sinpi/10(cospi/10+isinpi/10)`
`rArr |z|=2sinpi/10` and arg(z)`=pi/10`
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OBJECTIVE RD SHARMA ENGLISH-COMPLEX NUMBERS -Chapter Test
  1. The amplitude of sin (pi)/(5) +i(1-cos"" (pi)/(5)) is

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  2. The locus of the center of a circle which touches the circles |z-z1|=a...

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  3. Prove that for positive integers n(1) and n(2), the value of express...

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  4. The value of abs(sqrt( 2i) - sqrt(2i)) is :

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  5. Prove that the triangle formed by the points 1,(1+i)/(sqrt(2)),a n di ...

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  6. The value of ((1+ i sqrt(3))/(1-isqrt(3)))+ ((1-isqrt(3))/(1+isqrt(3)...

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  7. If alpha+ibeta=tan^(-1) (z), z=x+iy and alpha is constant, the locus o...

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  8. If cosA+cosB+cosC=0,sinA+sinB+sinC=0andA+B+C=180^(@) then the value of...

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  9. Find the sum 1xx(2-omega)xx(2-omega^(2))+2xx(-3-omega)xx(3-omega^(2))+...

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  10. The value of the expression (1+(1)/(omega))+(1+(1)/(omega^(2)))+(2+(1)...

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  11. The condition that x^(n+1)-x^(n)+1 shall be divisible by x^(2)-x+1 is ...

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  12. The expression (1+i)^(n1)+(1+i^(3))^(n2) is real iff

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  13. If |{:(6i,3i,1),(4,3i,-1),(20,3,i):}|=x+iy, then (x, y) is equal to

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  14. If cosalpha+2cosbeta+3cosgamma=sinalpha+2sinbeta+3singamma=0,t h e nt ...

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  15. If cosalpha+2cosbeta+3cosgamma=sinalpha+2sinbeta+3singamma=0,t h e nt ...

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  16. Sum of the series sum(r=0)^n (-1)^r ^nCr[i^(5r)+i^(6r)+i^(7r)+i^(8r)] ...

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  17. If az(1)+bz(2)+cz(3)=0 for complex numbers z(1),z(2),z(3) and real num...

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  18. If 2z1-3z2 + z3=0, then z1, z2 and z3 are represented by

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  19. If Re((z+4)/(2z-1)) = 1/2 then z is represented by a point lying on

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  20. The vertices of a square are z(1),z(2),z(3) and z(4) taken in the anti...

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  21. Let lambda in R . If the origin and the non-real roots of 2z^2+2z+lam...

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