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Verify the following derivative formulas using the Quotient Rule. $$\frac{d}{d x}(\sec x)=\sec x \tan x$$

Short Answer

Expert verified
Question: Verify that the derivative of the secant function, \(\sec x\), is given by the formula \(\frac{d}{dx}(\sec x)=\sec x \tan x\). Answer: We verified the given derivative formula using the quotient rule and found that $$\frac{d}{dx}(\sec x)=\sec x \tan x$$ as claimed.

Step by step solution

01

Rewrite the secant function

We will rewrite the secant function as a quotient. Remember that \(\sec x = \frac{1}{\cos x}\). Now we have a quotient of two functions, with \(f(x) = 1\) and \(h(x) =\cos x\).
02

Apply the quotient rule

Now apply the quotient rule with \(f(x) = 1\) and \(h(x) = \cos x\): $$\frac{d}{dx}(\frac{1}{\cos x})=\frac{\cos x\frac{d(1)}{dx}-1\frac{d(\cos x)}{dx}}{(\cos x)^2}$$
03

Evaluate the derivatives

Find the derivatives of the numerator functions: $$\frac{d(1)}{dx}=0\text{ and }\frac{d(\cos x)}{dx}=-\sin x$$ Then substitute these derivatives back into the equation from step 2: $$\frac{d}{dx}(\frac{1}{\cos x})=\frac{\cos x(0)-1(-\sin x)}{(\cos x)^2}$$
04

Simplify the expression

Simplify the expression to get the final result: $$\frac{d}{dx}(\sec x)=\frac{\sin x}{(\cos x)^2}$$ Now, recall the trigonometric identity \(\tan x = \frac{\sin x}{\cos x}\). Using this identity, we can further rewrite the expression as: $$\frac{d}{dx}(\sec x)=\frac{1}{\cos x} \cdot \frac{\sin x}{\cos x} = \sec x \tan x$$ As our result matches the given formula, we have successfully verified the derivative formula: $$\frac{d}{d x}(\sec x)=\sec x \tan x$$

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Most popular questions from this chapter

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