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cos^(2)5^(@)+cos^(2)10^(@)+cos^(2)15^(@)...

`cos^(2)5^(@)+cos^(2)10^(@)+cos^(2)15^(@)+.....+cos^(2) 90^(@)=`

A

7

B

`17/2`

C

`19/2`

D

`15/2`

Text Solution

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The correct Answer is:
B
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AAKASH SERIES-TRIGONOMERTIC RATIOS-PRACTICE EXERCISE
  1. If alpha , beta are complementary angles , sin alpha = 3//5 , then s...

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  2. Prove that sin^(2)5^(@) +sin^(2)10^(@) + sin^(2)15^(@)+...+sin^(2)90^(...

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  3. cos^(2)5^(@)+cos^(2)10^(@)+cos^(2)15^(@)+.....+cos^(2) 90^(@)=

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  4. cos^(@)cos2^(@)cos3^(@).......cos179^(@)=

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  5. tan10^(@) tan 20^(@) tan 30^(@) tan 40^(@) tan 50^(@) tan 60^(@) tan 7...

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  6. [(Tan ( pi - x) Tan (1.5 pi + x))/(Cos^(2)(x-1.5pi))-(Cos(1.5pi + x))/...

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  7. If cos A = 3/4 then (2cos A + 3 sin A)/(4 cos A - sin A) =

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  8. If theta is acute and (1-a^(2)) sin theta =(1+ a^(2)) cos theta , t...

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  9. If cot theta=-3//4 and theta is not in the second quadrant , then ...

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  10. If tan 20^(@) = lambda , " then " (tan 250^@ + tan 340^(@))/(tan 200^...

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  11. 3(sin x + cos x )^(4) + 6(sin x - cos x )^(2) + 4(sin^(6) x + cos^(6) ...

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  12. If k=( sec A + tan A) ( sec B+ tan B) sec C + tan C)=(sec A - tan A)(s...

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  13. In Delta le ABC, 3 tan A+4=0 then the quadratic equation whose roots a...

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  14. If sin theta , cos theta are ther roots of the equation ax^(2)-bx+c...

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  15. If (x)/(a) cos theta + (y)/(b) sin theta = 1 , (x)/(a) sin theta - (y...

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  16. If x = h + p Sec alpha, y = k + q cosec alpha then ((p)/(x-h))^(2) +((...

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  17. If x=a("cosec" theta + cot theta ) , y=b( " cosec " theta - cot theta ...

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  18. (1+cosec theta - cot theta)/(1+cosec theta + cot theta)=

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  19. (1)/(sec^(4) alpha ) +(1)/("cosec"^(4) alpha ) +(2)/(sec^(2) alpha + ...

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  20. ( cos^(3) A + sin^(3) A )/( cos A + sin A ) + (cos^(3) A - sin^(3)A)/(...

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