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cos^2alpha+cos^2(alpha+120^0)+cos^2(alph...

`cos^2alpha+cos^2(alpha+120^0)+cos^2(alpha-120^0)=3/2`

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cos^(2)alpha+cos^(2)(alpha+120^(@))+cos^(2)(alpha-120^(@))=(3)/(2)

cos^(2)alpha+cos^(2)(alpha+120^(@))+cos^(2)(alpha-120^(@))=?

cos ^(2) alpha + cos ^(2) (alpha + 120^(@)) + cos ^(2) (alpha - 120^(@)) is equal to

cos alpha+cos(120^(@)+alpha)+cos(120^(@)-alpha)=0

If A = cos ^(2) alpha + cos ^2(alpha + beta)- 2 cos alpha cos beta cos (alpha + beta), then

To prove ((1)/(sec^(2)alpha-cos^(2)alpha)+(1)/(cos ec^(2)alpha-sin^(2)alpha))cos^(2)alpha sin^(2)alpha=(1-sin^(2)alpha cos^(2)alpha)/(2+sin^(2)alpha cos^(2)alpha)

Prove that: cos ^ (2) alpha + cos ^ (2) (alpha + beta) -2cos alpha cos beta cos (alpha + beta) = sin ^ (2) beta

If alpha is any real nubmer then: (sin^4alpha+sin^2alpha.cos^2alpha+cos^2alpha)/(cos^4alpha+sin^2alpha.cos^2alpha+sin^2alpha)=.... (a) 1 (b)2 (c) 3 (d) none of these

cos^(3)alpha+cos^(3)(120+alpha)+cos(120-alpha)=3(sqrt(3))/(4), then the general solution of alpha is

MODERN PUBLICATION-TRIGONOMETRY-Exercise 3(g)Long Answer type Question-I
  1. Prove that: "sin" 4A=4 sin A cos^(3)A-4 cos A "sin"^(3)A.

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  2. If cos theta=(1)/(2)(alpha+(1)/(alpha)),prove that: (i) 2 cos 2thet...

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  3. If x+(1)/(x)=2costheta, then find the valueof x^(3)+(1)/(x^(3)).

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  4. Prove that: (i) cos A cos(60^(@)-A)cos (60^(@)+A)=(1)/(4)cos 3A ...

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  5. cos^2alpha+cos^2(alpha+120^0)+cos^2(alpha-120^0)=3/2

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  6. If tan^2theta=1+2tan^2phi then show that cos2theta+sin^2phi=0

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  7. Find sin x/2 ,cos x/2 and t a n x/2 of the following : s in" "x" "=1/...

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  8. (i) If "tan""(x)/(2)=(m)/(n),prove that m sin x+n cos x=n. (ii) If...

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  9. Prove that (cos^(3)theta-cos 3theta)/(cos theta)+("sin"^(3)theta+"sin"...

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  10. Evaluate: (i) "sin""(3pi)/(8) (ii) "sin""(5pi)/(24) (iii) "tan""(pi...

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  11. Prove that: s in^4pi/8+s in^4(3pi)/8+s in^4(5pi)/8+s in^4(7pi)/8=3/2

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  12. Prove that: (i) "sin"^(2)6x-"sin"^(2)4x="sin" 2x sin 10x (ii) c...

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  13. Find "sin" 7(1^(@))/(2),cos 7(1^(@))/(2) and "tan" 11(1^(@))/(4).

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  14. Prove that: "tan" 142(1^(@))/(2)=2+sqrt2-sqrt3-sqrt6.

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  15. Prove that cotxcot2x-cot2xcot3x-cot3xcotx=1

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  16. Prove that: (i) sin 3x+"sin" 2x-"sin" x =4 sin x cos((x)/(2))cos...

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  17. Prove that cos^2x+cos^2(x+pi/3)+cos^2(x-pi/3)=3/2

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  18. If cos theta=(cos phi-e)/(1-e cos phi),show that: "tan"(theta)/(2)...

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