Trigonometry (11th Edition)
Trigonometry (11th Edition)
11th Edition
ISBN: 9780134217437
Author: Margaret L. Lial, John Hornsby, David I. Schneider, Callie Daniels
Publisher: PEARSON
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10. no calculater way please 

**Trigonometric Identity Verification**

Show that \( \tan(x) + \cot(x) = \sec(x) \csc(x) \). (Verify this identity.)

**Verification:**

To verify the trigonometric identity, we will transform both sides of the equation to make them equal.

1. **Left Side:**

\[ \tan(x) + \cot(x) \]

We know that:

\[ \tan(x) = \frac{\sin(x)}{\cos(x)} \]
\[ \cot(x) = \frac{\cos(x)}{\sin(x)} \]

Combining these, we get:

\[ \tan(x) + \cot(x) = \frac{\sin(x)}{\cos(x)} + \frac{\cos(x)}{\sin(x)} \]

To add these fractions, find a common denominator:

\[ \tan(x) + \cot(x) = \frac{\sin^2(x) + \cos^2(x)}{\sin(x)\cos(x)} \]

Using the Pythagorean identity \( \sin^2(x) + \cos^2(x) = 1 \):

\[ \tan(x) + \cot(x) = \frac{1}{\sin(x)\cos(x)} \]

2. **Right Side:**

\[ \sec(x) \csc(x) \]

We know that:

\[ \sec(x) = \frac{1}{\cos(x)} \]
\[ \csc(x) = \frac{1}{\sin(x)} \]

Multiplying these, we get:

\[ \sec(x) \csc(x) = \frac{1}{\cos(x)} \cdot \frac{1}{\sin(x)} = \frac{1}{\sin(x)\cos(x)} \]

3. **Conclusion:**

Since both the left side and the right side simplify to:

\[ \frac{1}{\sin(x)\cos(x)} \]

the identity is verified. Therefore,

\[ \tan(x) + \cot(x) = \sec(x) \csc(x) \]

is true.
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Transcribed Image Text:**Trigonometric Identity Verification** Show that \( \tan(x) + \cot(x) = \sec(x) \csc(x) \). (Verify this identity.) **Verification:** To verify the trigonometric identity, we will transform both sides of the equation to make them equal. 1. **Left Side:** \[ \tan(x) + \cot(x) \] We know that: \[ \tan(x) = \frac{\sin(x)}{\cos(x)} \] \[ \cot(x) = \frac{\cos(x)}{\sin(x)} \] Combining these, we get: \[ \tan(x) + \cot(x) = \frac{\sin(x)}{\cos(x)} + \frac{\cos(x)}{\sin(x)} \] To add these fractions, find a common denominator: \[ \tan(x) + \cot(x) = \frac{\sin^2(x) + \cos^2(x)}{\sin(x)\cos(x)} \] Using the Pythagorean identity \( \sin^2(x) + \cos^2(x) = 1 \): \[ \tan(x) + \cot(x) = \frac{1}{\sin(x)\cos(x)} \] 2. **Right Side:** \[ \sec(x) \csc(x) \] We know that: \[ \sec(x) = \frac{1}{\cos(x)} \] \[ \csc(x) = \frac{1}{\sin(x)} \] Multiplying these, we get: \[ \sec(x) \csc(x) = \frac{1}{\cos(x)} \cdot \frac{1}{\sin(x)} = \frac{1}{\sin(x)\cos(x)} \] 3. **Conclusion:** Since both the left side and the right side simplify to: \[ \frac{1}{\sin(x)\cos(x)} \] the identity is verified. Therefore, \[ \tan(x) + \cot(x) = \sec(x) \csc(x) \] is true.
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