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Question

Evaluate the given expression. \[\frac{5}{1+\cot^2\theta} + \frac{3}{1+\tan^2\theta} + 2\cos^2\theta\]

This question was previously asked in
SSC CGL 2024 (Tier-I) Previous Year Paper (17-Sep-2024) (Shift 3)
The correct answer is

5

Step 1: Simplify the Trigonometric Identities

Recall the following identities:

1. \(1 + \cot^2 \theta = \csc^2 \theta\)

2. \(1 + \tan^2 \theta = \sec^2 \theta\)

3. \(\csc \theta = \frac{1}{\sin \theta}\)

4. \(\sec \theta = \frac{1}{\cos \theta}\)

Substitute these into the expression:

\[\frac{5}{\csc^2 \theta} + \frac{3}{\sec^2 \theta} + 2 \cos^2 \theta\]

Step 2: Rewrite in Terms of Sine and Cosine

Since \(\csc \theta = \frac{1}{\sin \theta}\) and \(\sec \theta = \frac{1}{\cos \theta}\):

\[\frac{5}{\csc^2 \theta} = 5 \sin^2 \theta\]

\[\frac{3}{\sec^2 \theta} = 3 \cos^2 \theta\]

So the expression becomes:

\[5 \sin^2 \theta + 3 \cos^2 \theta + 2 \cos^2 \theta\]

Step 3: Combine Like Terms

Combine the \(\cos^2 \theta\) terms:

\[5 \sin^2 \theta + (3 \cos^2 \theta + 2 \cos^2 \theta) = 5 \sin^2 \theta + 5 \cos^2 \theta\]

Factor out the 5:

\[5 (\sin^2 \theta + \cos^2 \theta)\]

Step 4: Apply the Pythagorean Identity

We know that \(\sin^2 \theta + \cos^2 \theta = 1\), so:

\[5 (1) = 5\]

Final Answer:

The expression simplifies to 5.

From the given options, the correct answer is 4. 5.

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Similar Questions

  1. If A is an acute angle and tanA + cotA = 2, find the value of 7tan⁸A – 6cot⁸A + 8sec²A.

  2. If p = sinA / (1 + cosA), then sinA / (1 - cosA) is equal to:

  3. In a ΔABC, right-angled at B if tanC = √3, then find (sin²C + cos²C) / (1 + cot²C).

  4. If 2 Cot x = 5, then what is (2 Cos x - Sin x) / (2 Cos x + Sin x) equal to?

  5. For any acute angle θ, sin²θ + cos²θ = 1. Then the value of cos²θ + cos⁴θ is:

  6. If p sin A − cos A = 1, then p2 − (1 + p2) cos A equals:

  7. If (48° + k) is an acute angle and sin(48° + k) = cos13°, what is the value of k (in °)?

  8. If secθ = 4/3, what is the value of tan²θ + tan⁴θ?

  9. Using
    \[ \cot(A − B) = \frac{\cot A \cot B + 1}{\cot B − \cot A} \]
    Find the value of cot 15°

  10. If \[ \frac{\sec \alpha + \tan \alpha}{\sec \alpha - \tan \alpha} = \frac{7}{4}, \] then find the value of \( \csc \alpha \).


Important Questions from Trigonometry

  1. If A is an acute angle and tanA + cotA = 2, find the value of 7tan⁸A – 6cot⁸A + 8sec²A.

  2. If p = sinA / (1 + cosA), then sinA / (1 - cosA) is equal to:

  3. In a ΔABC, right-angled at B if tanC = √3, then find (sin²C + cos²C) / (1 + cot²C).

  4. If 2 Cot x = 5, then what is (2 Cos x - Sin x) / (2 Cos x + Sin x) equal to?

  5. For any acute angle θ, sin²θ + cos²θ = 1. Then the value of cos²θ + cos⁴θ is:

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