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If A+B+C=pi, prove that : cos2A+cos2B-co...

If `A+B+C=pi`, prove that : `cos2A+cos2B-cos2C=1-4sinA sinB cosC`

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MARVEL PUBLICATION-TRIGONOMETRIC FUNCTIONS OF COMPOUND ANGLES AND FACTORIZATION FORMULAE-MCQs
  1. If A+B+C=pi, prove that : cos2A+cos2B-cos2C=1-4sinA sinB cosC

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  2. sin10 5^(@)+cos10 5^(@)=

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  3. sin((pi)/(3)+A).cos((pi)/(3)+B)-cos((pi)/(3)+A).sin((pi)/(3)+B)=...

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  4. If 0 ltA lt(pi//2)and0 ltB lt(pi//2), then angle (A-B) lies in…….. Qua...

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  5. If 0 ltA lt(pi//2)and0 ltB lt(pi//2), then angle (A-B) lies in…….. Qua...

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  6. If sinA=3//5 andcosB=9//41, where A,B are both in the first quadrant, ...

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  7. If sinalpha=15//17, (pi//2) ltalpha ltpi and secbeta=13//12, (3pi//2)...

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  8. If tanalpha=3//4 ,alpha in third quadrant, and cosbeta=9//41,beta, in ...

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  9. If sintheta=1//2,cosphi=12//13, where theta lies in the second quadran...

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  10. For any angles A and B, sin(A+B). sin(A-B)=......

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  11. For any angles A and B, cos(A+B).cos(A-B)=…..

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  12. 1+tanA.tan(A//2)=…..

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  13. ( tan3A + tanA)/(tan3A -tan A)=..

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  14. For any angles A,B,C. (sin(A-B))/(cosA.cosB)+(sin(B-C))/(cosB.cosC)+(s...

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  15. sinx+cosx=sqrt2.sin(....)

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  16. cosx-sinx=sqrt2.cos(....)

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  17. tan20^@+tan25^@+tan20^@.tan25^@=....

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  18. tan4 0^@+2tan1 0^@ is equal to

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  19. If A+B=45^@ then (1+tanA)(1+tanB)=

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  20. If 2sin(x+60^@)=cos(x-30^@), then : tan=…..

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  21. tan(45^(@)+A)tan(45^(@)-A)=

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