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Find the value of : cos^(2)60^(@)+sec^...

Find the value of :
`cos^(2)60^(@)+sec^(2)30^(@)+tan^(2)45^(@)`

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To find the value of the expression \( \cos^2(60^\circ) + \sec^2(30^\circ) + \tan^2(45^\circ) \), we will calculate each term step by step. ### Step 1: Calculate \( \cos^2(60^\circ) \) We know that: \[ \cos(60^\circ) = \frac{1}{2} \] Thus, \[ \cos^2(60^\circ) = \left(\frac{1}{2}\right)^2 = \frac{1}{4} \] ### Step 2: Calculate \( \sec^2(30^\circ) \) The secant function is the reciprocal of the cosine function: \[ \sec(30^\circ) = \frac{1}{\cos(30^\circ)} \] We know that: \[ \cos(30^\circ) = \frac{\sqrt{3}}{2} \] Therefore, \[ \sec(30^\circ) = \frac{1}{\frac{\sqrt{3}}{2}} = \frac{2}{\sqrt{3}} \] Now, we calculate \( \sec^2(30^\circ) \): \[ \sec^2(30^\circ) = \left(\frac{2}{\sqrt{3}}\right)^2 = \frac{4}{3} \] ### Step 3: Calculate \( \tan^2(45^\circ) \) We know that: \[ \tan(45^\circ) = 1 \] Thus, \[ \tan^2(45^\circ) = 1^2 = 1 \] ### Step 4: Combine all the values Now, we can combine all the calculated values: \[ \cos^2(60^\circ) + \sec^2(30^\circ) + \tan^2(45^\circ) = \frac{1}{4} + \frac{4}{3} + 1 \] ### Step 5: Find a common denominator The common denominator for \( 4 \), \( 3 \), and \( 1 \) is \( 12 \): \[ \frac{1}{4} = \frac{3}{12}, \quad \frac{4}{3} = \frac{16}{12}, \quad 1 = \frac{12}{12} \] Now, we can add these fractions: \[ \frac{3}{12} + \frac{16}{12} + \frac{12}{12} = \frac{3 + 16 + 12}{12} = \frac{31}{12} \] ### Final Answer Thus, the value of the expression is: \[ \frac{31}{12} \]
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ICSE-TRIGONOMETRICAL RATIOS OF STANDARD ANGLES-EXERCISE 23(A)
  1. Find the value of : cosec^(2)60^(@)-tan^(2)30^(@)

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  2. Find the value of : sin^(2)30^(@)+cos^(2)30^(@)+cot^(2)45^(@)

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  3. Find the value of : cos^(2)60^(@)+sec^(2)30^(@)+tan^(2)45^(@)

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  4. Find the value of : tan^(2)30^(@)+tan^(2)45^(@)+tan^(2)60^(@)

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  5. Find the value of : (tan45^(@))/(cosec30^(@))+(sec60^(@))/(cot45^(@)...

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  6. Find the value of : 3sin^(2)30^(@)+2tan^(2)60^(@)-5cos^(2)45^(@)

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  7. Prove that : sin60^(@)cos30^(@)+cos60^(@).sin30^(@)=1

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  8. Prove that : cos30^(@).cos60^(@)-sin30^(@).sin60^(@)=0

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  9. Prove that : cosec^(2)45^(@)-cot^(2)45^(@)=1

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  10. Prove that : cos^(2)30^(@)-sin^(2)30^(@)=cos60^(@)

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  11. Prove that : ((tan60^(@)+1)/(tan60^(@)-1))^(2)=(1+cos30^(@))/(1-cos3...

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  12. Prove that : 3cosec^(2)60^(@)-2cot^(2)30^(@)+sec^(2)45^(@)=0.

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  13. Prove that : sin(2 times 30^(@))=(2tan30^(@))/(1+tan^(2)30^(@))

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  14. Prove that : cos(2 times 30^(@))=(1-tan^(2)30^(@))/(1+tan^(2)30^(@))

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  15. Prove that : tan(2 times 30^(@))=(2tan30^(@))/(1-tan^(2)30^(@))

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  16. ABC is an isosceles right-angled triangle. Assuming AB = BC = x, find ...

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  17. Prove that : sin60^(@)=2sin30^(@)cos30^(@).

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  18. Prove that : 4(sin^(4)30^(@)+cos^(4)60^(@))-3(cos^(2)45^(@)-sin^(2)...

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  19. If sinx =cosx and x is acute, state the value of x.

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  20. If secA=cosecA" and "0^(@) le A le 90^(@), state the value of A.

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