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Show that sin^2 5^0+sin^2 10^0+sin^2 15^...

Show that `sin^2 5^0+sin^2 10^0+sin^2 15^0++sin^2 90^0=9 1/2dot`

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`L.H.S.=(sin^2 5^@+sin^2 85^@)+(sin^2 10^@+sin^2 80^@)+...`
`+(sin^2 40^@+sin^2 50^@)+(sin^2 45^@+sin^2 90^@)`
`(sin^2 5^@+sin^2 5^@)+(sin^2 10^@+sin^2 10^@)+...`
`+(sin^2 40^@+sin^2 40^@)+(sin^2 45^@+sin^2 45^@)`
`=(1+1+1+1+1+1+1+1)`
`+(1/sqrt2)^(2)+1=9 1/2=R.H.S.`
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CENGAGE-TRIGONOMETRIC FUNCTIONS -SINGLE CORRECT ANSWER TYPE
  1. Show that sin^2 5^0+sin^2 10^0+sin^2 15^0++sin^2 90^0=9 1/2dot

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  2. The circular wire of diameter 10 cm is cut and placed along the circum...

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  3. sintheta/(1-cottheta)+costheta/(1-tantheta)= (a)theta (b)1 (c)costh...

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  4. If theta in (pi//4, pi//2) and sum(n=1)^(oo)(1)/(tan^(n)theta)=sin the...

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  5. The value of (tan^(2)20^(@)-sin^(2)20^(@))/(tan^(2)20^(@).sin^(2)20^(@...

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  6. If 15 sin^(4)alpha+10cos^(4)alpha=6, then the value of 8 cosec^(6)alph...

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  7. In DeltaABC, if sin A + sin B + sin C= 1 + sqrt2 and cos A+cos B+cos...

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  8. If (sin^(2)x-2cos^(2)x+1)/(sin^(2)x+2cos^(2)x-1)=4, then the value of ...

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  9. If sintheta,tantheta,costheta are in G.P. then 4sin^2theta-3sin^4theta...

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  10. If tantheta-cottheta=aandsintheta+costheta=b(b^2-1)^2(a^2+4) is equal...

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  11. The least value of 18 sin^(2)theta+2 cosec^(2)theta-3 is

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  12. If tan^2 alpha tan^2 beta + tan^2 beta tan^2 gamma + tan^2 gamma tan^2...

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  13. If x,y,z be all positive acute angles then the least value of tanx(cot...

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  14. Three circles each of radius 1, touch one another externally and they ...

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  15. If (cos alpha)/(cos A)+(sin alpha)/(sin A)+(sin beta)/(sin A)=1, where...

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  16. Consider angles alpha = (2n+(1)/(2))pi pm A and beta = m pi +(-1)^(m)(...

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  17. Which of the following is true ?

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  18. If the angle A of a triangle ABC is given by the equation 5 cos A + 3 ...

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  19. Which of the following is greatest ?

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  20. The number of value/values of x for which sin y=x^(2)-2x si possible i...

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  21. Which of the following is not correct ?

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