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Prove that, in any triangle ABC, cos B=(...

Prove that, in any triangle ABC, `cos B=(c^2+a^2-b^2)/(2ca)`.

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BETTER CHOICE PUBLICATION-VECTOR ALGEBRA -PREVIOUS YEARS BOARD.S QUESTIONS FOR PRACTICE (MCQ)
  1. Using vectors, prove that cos(alpha-beta)=cosalpha cosbeta+sinalphas...

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  2. With the help of vector method, prove that,cosA=(b^2+c^2-a^2)/(2bc)

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  3. Prove that, in any triangle ABC, cos B=(c^2+a^2-b^2)/(2ca).

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  4. Find vecaxxvecb, if veca=2hati+hatj+3hatk and vecb=3hati+5hatj-2hatk

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  5. Find |vecaxxvecb|, if veca=3hati+4hatjand vecb=hati-hatj+hatk

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  6. Find the unit vector perpendicular to the vector veca=-hati-2hatj+3h...

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  7. Find the unit vector perpendicular to the vector veca=4hati-3hatj-ha...

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  8. Using vector, prove that sin(A+B)=sinAcosB+cosAsinB

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  9. Find the area of a parallelogram whose adjacent sides are : 3hati-4h...

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  10. Find the area of a parallelogram whose adjacent sides are : 3hati+ha...

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  11. Find the area of parallelogram whose adjacent sides are given by vecto...

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  12. If veca+vecb+vecc=vec0, show that vecaxxvecb=veccxxveca. Interpret the...

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  13. veca=hati-2hatj+3hatk and vecb=2hati+3hatj-5hatk find vecaxxvecb and v...

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  14. Find the angle between two vectors veca and vecb with magnitudes sqrt3...

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  15. The magnitude of the vector 2hati-6hatj-3hatk is :

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  16. Show that the three points with position vectors -2hati+3hatj+5hatk,ha...

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  17. The value of lambda for which the vectors veca=2hati+lambdahatj+hatk ...

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  18. Let veca=4hati+5hatj-hatk,vecb=hati-4hatj+5hatk and vecc=3hati+hatj-ha...

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  19. Find the scalar projection of vecb on veca where : veca=2hati-2hatj+ha...

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  20. If veca=2hati-2hatj+hatk,vecb=hati+2hatj-2hatk and vecc=2hati-hatj+4ha...

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