Solved on Jan 28, 2024

Find the secant squared of the inverse cotangent of xx. Select the correct answer.

STEP 1

Assumptions
1. We are looking to find the value of sec2(cot1x)\sec^2(\cot^{-1} x).
2. cot1x\cot^{-1} x represents the inverse cotangent function, which gives us an angle whose cotangent is xx.
3. The relationship between the trigonometric functions cotangent and secant will be used.
4. We will use the identity sec2θ=1+tan2θ\sec^2 \theta = 1 + \tan^2 \theta.

STEP 2

First, let's denote the angle whose cotangent is xx as θ\theta. Therefore, we have:
cotθ=x\cot \theta = x

STEP 3

We know that the cotangent of an angle in a right triangle is the adjacent side over the opposite side. Let's represent the adjacent side as xx and the opposite side as 11 (since cotθ=adjacentopposite=x\cot \theta = \frac{\text{adjacent}}{\text{opposite}} = x).

STEP 4

Using the Pythagorean theorem, we can find the hypotenuse hh of the right triangle with sides xx and 11.
h2=x2+12h^2 = x^2 + 1^2

STEP 5

Solve for the hypotenuse hh.
h=x2+1h = \sqrt{x^2 + 1}

STEP 6

Now, we can express the secant of θ\theta in terms of xx and hh. Secant is the reciprocal of cosine, and cosine is the adjacent side over the hypotenuse. Therefore:
secθ=1cosθ=hx\sec \theta = \frac{1}{\cos \theta} = \frac{h}{x}

STEP 7

Substitute the value of hh into the expression for secθ\sec \theta.
secθ=x2+1x\sec \theta = \frac{\sqrt{x^2 + 1}}{x}

STEP 8

Square the expression to find sec2θ\sec^2 \theta.
sec2θ=(x2+1x)2\sec^2 \theta = \left(\frac{\sqrt{x^2 + 1}}{x}\right)^2

STEP 9

Simplify the squared expression.
sec2θ=x2+1x2\sec^2 \theta = \frac{x^2 + 1}{x^2}

STEP 10

Now, we replace θ\theta with cot1x\cot^{-1} x to find sec2(cot1x)\sec^2(\cot^{-1} x).
sec2(cot1x)=x2+1x2\sec^2(\cot^{-1} x) = \frac{x^2 + 1}{x^2}

STEP 11

We can see that the expression matches one of the given options.
The solution is:
sec2(cot1x)=x2+1x2\sec^2(\cot^{-1} x) = \frac{x^2 + 1}{x^2}
Therefore, the correct answer is 1+x2x2\frac{1+x^2}{x^2}.

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