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Prove thatcos^2alpha+cos^2(120^@-alpha)+...

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

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Prove that cos alpha cos (120^(@) + alpha) cos (240^(@) + alpha) = 1/4 cos 3 alpha

Prove that, cos alpha + cos(120^(@) + alpha) + cos (120^(@) - alpha) = 0

Show that, cos^(2)alpha + cos^(2) (120^(@) - alpha) + cos^(2) (120^(@) + alpha) = 3/2.

Prove that : sec alpha+ sec (120^(@)+ alpha) sec (120^(@)-alpha)=-3 sec 3 alpha

Prove that, cos^(3) alpha + cos^(3) (120^(@) + alpha) + cos^(3) (240^(@) + alpha) = 3/4 cos 3 alpha

Prove that sin alpha + sin (120^(@) + alpha) + sin(240^(@)+ alpha)=0

Prove that, sin^(2) alpha + sin^(2) (120^(@) - alpha) + sin^(2) (120^(@) + alpha) = 3/2

If alpha= (2pi)/(7) , then prove that cos alpha+ cos 2 alpha+ cos 4alpha=-(1)/(2) . Hence, deduce that sin alpha+ sin 2alpha+ sin 4alpha=(sqrt(7))/(2)

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UNITED BOOK HOUSE-ANNUAL EXAMINATION QUESTION PAPERS 2014-EXERCISE
  1. In the expansion of (root(3)(2)+1/root(3)(3))^nthe rationof the 7th te...

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  2. If the sum of sirst n terms of a G.P is p.sum of its first 2n terms is...

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  3. The equations of two sides of a square are 5x+12y-10=0 and 5x+12y+29=0...

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  4. If the straight line x/a+y/b=1is parallel to the line 4x+3y=6 and pas...

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  5. Find the equations of the circles which pass through the origin and cu...

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  6. Evaluate:lim(xrarr0)(sin(x^2+4x))/(x^3-5x^2+2x)

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  7. Find from the first principle,the derivative of tan 2x at x=pi/8

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  8. Show that the following statement is true by the method of contraposit...

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  9. Prove the following by contradiciton ."The sum of a rational and an ir...

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  10. What is the probability that a year,selected at random,in between 2001...

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  11. For a group of 200 students the mean and S.D of marks obtained by them...

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  12. Prove thatcos^2alpha+cos^2(120^@-alpha)+cos^2(120^@+alpha)=3/2

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  13. Prove that tan70^(@)=2tan50^(@)+tan20^(@).

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  14. Draw the structure of the following: SF4

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  15. state the fundamental theorm of algebra and solve the equation 3x^2-5i...

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  16. How many numbers lying between 100 and 1000 can be formed with the dig...

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  17. If S1,S2...Smdenote the sums of n terms of m numbers of A.P is whose f...

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  18. Prove that the least focal chord of a parabolaa is it rectum.

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  19. Find the equation of a hyperbola having coodinates of its vertices (+-...

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  20. Find the equation of an ellipse whose eccentricity is 1/2,coordinates ...

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