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Question

For the following two (02) items: 

Let $\sin\theta+\cos\theta = p$  and $\sec\theta+\text{cosec}\theta = q$, where $p \neq 1$.

What is $\tan\theta + \cot\theta$ equal to?

This question was previously asked in
CDS 2 2025 Maths Question Paper (14-Sep-2025)
The correct answer is
$\frac{q}{p}$

Solving Trigonometric Expression tanθ + cotθ

This solution explains how to find the value of the trigonometric expression \(\tan\theta + \cot\theta\)$ given specific relationships involving \(\sin\theta\), \(\cos\theta\), \(\sec\theta\),\)$ and \(\text{cosec}\theta\)$.

Understanding the Given Information

We are provided with two equations:

  • \(\sin\theta + \cos\theta = p\)$
  • \(\sec\theta + \text{cosec}\theta = q\)$

We are also given the condition that \(\_p \neq 1\)$.

Simplifying the Target Expression

The expression we need to evaluate is \(\tan\theta + \cot\theta\)$. Let's rewrite this in terms of \(\sin\theta\)$ and \(\cos\theta\)$:

\begin{equation*} \tan\theta + \cot\theta = \frac{\sin\theta}{\cos\theta} + \frac{\cos\theta}{\sin\theta} \end{equation*}$

To add these fractions, we find a common denominator:

\begin{equation*} \frac{\sin^2\theta + \cos^2\theta}{\sin\theta \cos\theta} \end{equation*}$

Using the fundamental trigonometric identity \(\sin^2\theta + \cos^2\theta = 1\)$, the expression simplifies to:

\begin{equation*} \frac{1}{\sin\theta \cos\theta} \end{equation*}$

So, our goal now is to find the value of \(\sin\theta \cos\theta\)$ using the given information.

Finding the Value of \( \sin\theta \cos\theta \)

Let's use the first given equation, \(\sin\theta + \cos\theta = p\)$. We can square both sides of this equation:

\begin{equation*} (\sin\theta + \cos\theta)^2 = p^2 \end{equation*}$

Expanding the left side gives:

\begin{equation*} \sin^2\theta + \cos^2\theta + 2\sin\theta \cos\theta = p^2 \end{equation*}$

Substituting \(\sin^2\theta + \cos^2\theta = 1\)$:

\begin{equation*} 1 + 2\sin\theta \cos\theta = p^2 \end{equation*}$

Rearranging to solve for \(\sin\theta \cos\theta\)$:

\begin{equation*} 2\sin\theta \cos\theta = p^2 - 1 \end{equation*}$

\begin{equation*} \sin\theta \cos\theta = \frac{p^2 - 1}{2} \end{equation*}$

Now let's use the second given equation, \(\sec\theta + \text{cosec}\theta = q\)$. Rewrite \(\sec\theta\)$ and \(\text{cosec}\theta\)$ in terms of \(\sin\theta\)$ and \(\cos\theta\)$:

\begin{equation*} \frac{1}{\cos\theta} + \frac{1}{\sin\theta} = q \end{equation*}$

Combine the fractions on the left side:

\begin{equation*} \frac{\sin\theta + \cos\theta}{\sin\theta \cos\theta} = q \end{equation*}$

We know that \(\sin\theta + \cos\theta = p\)$. Substitute this into the equation:

\begin{equation*} \frac{p}{\sin\theta \cos\theta} = q \end{equation*}$

Now, solve for \(\sin\theta \cos\theta\)$:

\begin{equation*} \sin\theta \cos\theta = \frac{p}{q} \end{equation*}$

Calculating the Final Value

We established earlier that \(\tan\theta + \cot\theta = \frac{1}{\sin\theta \cos\theta}\)$.

Using the value \(\sin\theta \cos\theta = \frac{p}{q}\)$ derived from the second equation:

\begin{equation*} \tan\theta + \cot\theta = \frac{1}{\frac{p}{q}} \end{equation*}$

Simplifying this compound fraction gives:

\begin{equation*} \tan\theta + \cot\theta = \frac{q}{p} \end{equation*}$

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Similar Questions

  1. If \(\sqrt{2+\sqrt{2+\sqrt{2+\sqrt{2+...}}}} = \text{cosec}\theta\), then what is \(\sin\theta\) equal to?

  2. If \(2 \tan\theta = \sec^2\theta-2\), where \(0 < \theta < \pi /2\), then what is \(\cot\theta\) equal to?
  3. What is \(\frac{\tan^2 \alpha}{\tan^2 \beta}\) equal to?
  4. If \(\alpha\) and \(\beta\) are complementary angles, then which one of the following is correct?
  5. What is \(\sec\theta\) equal to?
  6. What is \(\tan\theta\) equal to?
  7. What is the relation between \(p\) and \(q\)?
  8. Consider the following statements :
    1. In a triangle ABC, if \(\sin A + \sin B + \sin C = \frac{3\sqrt{3}}{2}\), then the triangle can be equilateral.
    2. In a triangle ABC, if \(\cos A + \cos B + \cos C = \frac{3}{2}\), then the triangle can be equilateral.
    Which of the statements given above is/are correct?
  9. What is \((1 + \tan\alpha \tan\beta)^2 + (\tan\alpha - \tan\beta)^2\) equal to ?

  10. Consider the following statements :

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    II. \(\cot 25^\circ - \tan 25^\circ\) is negative

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Important Questions from Trigonometry

  1. (secθ + tanθ)/(secθ - tanθ)  is equal to:

  2. If tan 45°, cot θ then the value of θ, in radians is

  3. ABC is a triangle If sin (A+B)/2 = √3/2, then the value of sin C/2 is

  4. The angles of elevation of the top of a temple, from the foot and the top of a building 30 m high, are 60° and 30° respectively. Then height of the temple is

  5. The value of sin θ and cos θ when the angle θ is 0 ≤ θ ≤ 90°, is ______

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