Math Problem Statement

cotx/secx=cscx-sinx

Solution

To verify the identity cotxsecx=cscxsinx\frac{\cot x}{\sec x} = \csc x - \sin x, let's simplify the left-hand side (LHS) and right-hand side (RHS) separately.

Step 1: Express LHS in terms of basic trigonometric functions

cotxsecx=cosxsinx1cosx=cosxcosxsinx=cos2xsinx\frac{\cot x}{\sec x} = \frac{\frac{\cos x}{\sin x}}{\frac{1}{\cos x}} = \cos x \cdot \frac{\cos x}{\sin x} = \frac{\cos^2 x}{\sin x}

Step 2: Simplify RHS

cscxsinx=1sinxsinx\csc x - \sin x = \frac{1}{\sin x} - \sin x Convert the terms to a common denominator: cscxsinx=1sin2xsinx\csc x - \sin x = \frac{1 - \sin^2 x}{\sin x} Use the Pythagorean identity 1sin2x=cos2x1 - \sin^2 x = \cos^2 x: cscxsinx=cos2xsinx\csc x - \sin x = \frac{\cos^2 x}{\sin x}

Since the LHS and RHS are equal, the identity is verified:

cotxsecx=cscxsinx\frac{\cot x}{\sec x} = \csc x - \sin x


Do you want more details on any step?

Related Questions:

  1. How do you prove trigonometric identities?
  2. What are the fundamental trigonometric identities?
  3. How do you simplify expressions involving trigonometric functions?
  4. What is the Pythagorean identity in trigonometry?
  5. How do you solve equations involving multiple trigonometric functions?

Tip: Always convert trigonometric functions to basic terms (sine and cosine) when proving identities.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Trigonometric Identities
Simplification of Trigonometric Expressions

Formulas

cot x = cos x / sin x
sec x = 1 / cos x
csc x = 1 / sin x
Pythagorean Identity: 1 - sin^2 x = cos^2 x

Theorems

Pythagorean Identity

Suitable Grade Level

Grades 10-12