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Prove by vector method that cos(A+B)=c...

Prove by vector method that `cos(A+B)=cos AcosB-sinAsinBdot`

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CENGAGE PUBLICATION-VECTOR ALGEBRA-All Questions
  1. Prove that an angle inscribed in a semi-circle is a right angle usi...

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  2. If vec a.hat i= vec a.( hat i+ hat j)= vec a.( hat i+ hat j+ hat k) ...

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  3. Prove by vector method that cos(A+B)=cos AcosB-sinAsinBdot

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  4. If the scalar projection of vector x hat i- hat j+ hat k on vector 2...

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  5. If vec a=x hat i+(x-1) hat j+ hat k and vec b=(x+1) hat i+ hat j+a ha...

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  6. A unit vector a makes an angle pi/ 4 with z-axis. If a + i + j is a un...

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  7. if veca, vecb and vecc are there mutually perpendicular unit vectors a...

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  8. If vec a , vec b , and vec c be non-zero vectors such that no two ...

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  9. If vec p , vec q , vec r denote vector vec bxx vec c , vec cxx vec a...

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  10. If vec a and vec b be two non-collinear unit vector such that vec ...

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  11. Show that ( vec a- vec b)xx( vec a+ vec b)=2( vec axx vec b)dot

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  12. Prove that ( vec a.( vec bxx hat i)) hat i+( vec a.( vec bxx hat j)) h...

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  13. For any four vectors, vec a , vec b , vec c and vec d prove that vec...

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  14. If vec a , vec b, and vec c are three vectors such that vec axx ve...

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  15. If vec a= vec p+ vec q , vec pxx vec b=0a n d vec qdot vec b=0, then ...

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  16. If vec a= hat i+ hat j+ hat k and vec b= hat i-2 hat j+ hat k , then ...

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  17. If non-zero vectors veca and vecb are perpendicular to each ot...

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  18. If vec a , vec b , and vec c are mutually perpendicular vectors of ...

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  19. If vec a, vec b, vec c are unit vectors satisfying the condition veca+...

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  20. If three unit vectors vec a , vec b , and vec c satisfy vec a+ vec b...

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