Inverse Trigonometry
Inverse Trigonometric Identities
GRB_1000_SCQ
Grade Class 12
Question:
The number of values of x, for which tan⁻¹(1/x) = π + tan⁻¹x, 0 < x < 1 is:
Step-by-Step Solution
Key Concept: Using the identity tan⁻¹(1/x) = π/2 - tan⁻¹x for x > 0.
Step 1: Recall the identity for inverse tangent when x > 0.
For positive values of $x$, we have the fundamental identity:
$$\tan^{-1}\left(\frac{1}{x}\right) = \frac{\pi}{2} - \tan^{-1}(x)$$
Step 2: Substitute the identity into the given equation.
The given equation is:
$$\tan^{-1}\left(\frac{1}{x}\right) = \pi + \tan^{-1}(x)$$
Substituting the identity from Step 1:
$$\frac{\pi}{2} - \tan^{-1}(x) = \pi + \tan^{-1}(x)$$
Step 3: Rearrange to isolate $\tan^{-1}(x)$.
Moving all terms with $\tan^{-1}(x)$ to one side:
$$\frac{\pi}{2} - \pi = \tan^{-1}(x) + \tan^{-1}(x)$$
$$-\frac{\pi}{2} = 2\tan^{-1}(x)$$
Step 4: Solve for $\tan^{-1}(x)$.
Dividing both sides by 2:
$$\tan^{-1}(x) = -\frac{\pi}{4}$$
Step 5: Find the value of x.
Taking the tangent of both sides:
$$x = \tan\left(-\frac{\pi}{4}\right) = -1$$
Step 6: Check if the solution satisfies the given constraint.
We obtained $x = -1$, but the problem requires $0 < x < 1$.
Since $x = -1$ does not satisfy the constraint $0 < x < 1$, this solution is invalid.
**Conclusion:**
There are no values of $x$ in the interval $(0, 1)$ that satisfy the given equation.
**Answer: Option 1 (0)**
Correct Answer: 1