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the value of cos0+cos(pi/7)+cos(2pi/7)+c...

the value of `cos0+cos(pi/7)+cos(2pi/7)+cos(3pi/7)+cos(4pi/7)+cos(5pi/7)cos(6pi/7)`is (i) `1/2` (ii)`-1/2` (iii)`0` (iv)`1`

A

`1//2`

B

`-1//2`

C

0

D

1

Text Solution

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The correct Answer is:
D
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MOTION-TRIGNOMETRIC RATIOS & IDENTITIES -Exercise 2(Level -I)
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  2. If 3 sin x+ 4 cos x =5 then 4 sin x -3 cos x is equal to

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  3. the value of cos0+cos(pi/7)+cos(2pi/7)+cos(3pi/7)+cos(4pi/7)+cos(5pi/7...

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  5. If A+B+C=pi & cos A = cos B . Cos C then tan B . Tan C has the value e...

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  6. If 3 sin alpha=5 sin beta, then (tan((alpha+beta)/(2)))/(tan ((alpha-b...

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  7. If f( theta ) = sin ^(3)theta + sin ^(3)( theta + (2pi)/(3)) + sin ^(3...

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  8. If cosec A + cot A =11/2 , then tan A equal to

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  9. Prove that : (tan^(2)theta)/(1+tan^(2)theta)+(cot^(2)theta)/(1+cot^...

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  12. IF tan^2 theta=2 tan^2 phi +1 then find the value of cos 2 theta+sin^2...

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  13. If alpha in [(pi)/(2),pi] then the value of sqrt(1+ sin alpha)-sqrt(...

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  14. sqrt(2+sqrt(2+2cos 4 theta)), forall 0 lt theta lt pi//4 is

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  16. If A=tan6^(@) tan 42^(@) and B= cot 66^(@)cot 78^(@) then-

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  17. The value of 64sqrt(3)sin(pi/48)cos(pi/48)cos(pi/24)cos(pi/12)cos(pi/6...

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  18. Let a and b be positive number not equal to 1 and (3pi)/(2) lt theta ...

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  19. f(theta)=sin^4theta+cos^2theta then range of f(theta)

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  20. The value of cos(pi/19)+cos((3pi)/19)+cos((5pi)/19)+......+cos((17pi)/...

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