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If sec x + tan x =22/7 , find the value ...

If sec x + tan x =22/7 , find the value of tanx/2

A

the value of tan `(x)/(2)=(29)/(15)`

B

the value of tan `(x)/(2)=(29)/(15)`

C

the value of cosec x + cot `x=(29)/(15)`

D

thevalue of cosec x + cot `x=(15)/(29)`

Text Solution

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The correct Answer is:
To solve the problem where \( \sec x + \tan x = \frac{22}{7} \) and we need to find the value of \( \tan \frac{x}{2} \), we can follow these steps: ### Step 1: Rewrite the equation We know that: \[ \sec x = \frac{1}{\cos x} \quad \text{and} \quad \tan x = \frac{\sin x}{\cos x} \] Thus, we can rewrite the equation as: \[ \frac{1}{\cos x} + \frac{\sin x}{\cos x} = \frac{22}{7} \] Combining the fractions gives: \[ \frac{1 + \sin x}{\cos x} = \frac{22}{7} \] ### Step 2: Cross-multiply Cross-multiplying gives: \[ 7(1 + \sin x) = 22 \cos x \] This simplifies to: \[ 7 + 7 \sin x = 22 \cos x \] ### Step 3: Use the half-angle formulas We can express \( \sin x \) and \( \cos x \) in terms of \( \tan \frac{x}{2} \): \[ \sin x = \frac{2 \tan \frac{x}{2}}{1 + \tan^2 \frac{x}{2}} \quad \text{and} \quad \cos x = \frac{1 - \tan^2 \frac{x}{2}}{1 + \tan^2 \frac{x}{2}} \] ### Step 4: Substitute into the equation Substituting these into our equation gives: \[ 7 + 7 \left(\frac{2 \tan \frac{x}{2}}{1 + \tan^2 \frac{x}{2}}\right) = 22 \left(\frac{1 - \tan^2 \frac{x}{2}}{1 + \tan^2 \frac{x}{2}}\right) \] ### Step 5: Clear the denominators Multiply through by \( 1 + \tan^2 \frac{x}{2} \) to eliminate the fractions: \[ 7(1 + \tan^2 \frac{x}{2}) + 14 \tan \frac{x}{2} = 22(1 - \tan^2 \frac{x}{2}) \] ### Step 6: Rearrange the equation Expanding and rearranging gives: \[ 7 + 7 \tan^2 \frac{x}{2} + 14 \tan \frac{x}{2} = 22 - 22 \tan^2 \frac{x}{2} \] Combining like terms results in: \[ 29 \tan^2 \frac{x}{2} + 14 \tan \frac{x}{2} - 15 = 0 \] ### Step 7: Solve the quadratic equation Let \( y = \tan \frac{x}{2} \). The equation becomes: \[ 29y^2 + 14y - 15 = 0 \] Using the quadratic formula \( y = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a} \): \[ y = \frac{-14 \pm \sqrt{14^2 - 4 \cdot 29 \cdot (-15)}}{2 \cdot 29} \] Calculating the discriminant: \[ 14^2 = 196 \quad \text{and} \quad 4 \cdot 29 \cdot 15 = 1740 \] Thus, \[ b^2 - 4ac = 196 + 1740 = 1936 \] Taking the square root: \[ \sqrt{1936} = 44 \] Now substituting back: \[ y = \frac{-14 \pm 44}{58} \] Calculating the two possible values: 1. \( y = \frac{30}{58} = \frac{15}{29} \) 2. \( y = \frac{-58}{58} = -1 \) (not valid since \( \tan \frac{x}{2} \) cannot be negative) ### Final Answer Thus, the value of \( \tan \frac{x}{2} \) is: \[ \boxed{\frac{15}{29}} \]

To solve the problem where \( \sec x + \tan x = \frac{22}{7} \) and we need to find the value of \( \tan \frac{x}{2} \), we can follow these steps: ### Step 1: Rewrite the equation We know that: \[ \sec x = \frac{1}{\cos x} \quad \text{and} \quad \tan x = \frac{\sin x}{\cos x} \] Thus, we can rewrite the equation as: ...
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Knowledge Check

  • If sec 1.4=x, find the value of csc (2tan^(-1)x) .

    A
    0.33
    B
    0.87
    C
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    D
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