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If cosA+cos^2A=1 , then sin^2A+sin^4A= ...

If `cosA+cos^2A=1` , then `sin^2A+sin^4A=` `-1` (b) `0` (c) `1` (d) None of these

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True,
`therefore cosA + cos^(2)A=1`
`rArr cosA=1-cos^(2)A=sin^(2)A` `[therefore sin^(2)A+cos^(2)A=1]`
`rArr cos^(2)A=sin^(4)A`
`rArr 1-sin^(2)A=sin^(4)A`
`rArr sin^(2)A + sin^(4)A=1` `[therefore cos^(2)A= 1-sin^(2)A]`
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NCERT EXEMPLAR-INTRODUCTION TO TRIGoNOMETRY AND ITS APPLICATIONS-Introduction To Trigonometry And Its Applications
  1. The value of the expression (sin80^(@)-cos80^(@)) is negative.

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  2. sqrt((1-cos^(2)theta)sec^(2)theta)=tan theta

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  3. If cosA+cos^2A=1 , then sin^2A+sin^4A= -1 (b) 0 (c) 1 (d) None of ...

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  4. (tantheta+2)(2 tantheta+1)= ?

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  5. If the length of the shadow of a tower is increasing, then the angle o...

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  6. If a man standing on a platform 3 m above the surface of a lake observ...

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  7. The value of 2sintheta can be a+1/a, where a is a positive number and ...

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  8. costheta=(a^(2)+b^(2))/(2ab), where a and b are two distinct numbers s...

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  9. The angle of elevation theta of the top of a tower is 30^(@). If the h...

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  10. If the height of a tower and the distance of the point of observation ...

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  11. Prove that (sintheta)/(1+costheta) + (1+costheta)/(sintheta) = 2 cosec...

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  12. (tanA)/(1+secA) - (tanA)/(1-secA) = 2cosecA

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  13. If tan A=3/4, then sinAcosA =.

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  14. (sinalpha + cosalpha)(tanalpha + cotalpha) = secalpha + cosecalpha

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  15. Prove that (sqrt(3)+1)(3-cot30^@)=tan^3(60)^@-2sin60^@

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  16. Show that 1+cot^2alpha/(1+cosecalpha)=cosec alpha

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  17. tantheta+tan(9 0^(@)-theta)=secthetaxxsec(9 0^(@)-theta)

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  18. Find the angle of elevation of the Sun when the shadow of a pole h m ...

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  19. If sqrt(3)tantheta=1 then find value of sin^2theta-cos^2theta

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  20. A ladder 15 m long just reaches the top of a vertical wall. If the ...

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