Math Problem Statement

csc theta - sin theta = cot theta cos theta

Solution

To verify or simplify the equation cscθsinθ=cotθcosθ\csc \theta - \sin \theta = \cot \theta \cos \theta, let's start by rewriting each trigonometric term in terms of sine and cosine.

Step 1: Rewrite in terms of sine and cosine

  1. Rewrite cscθ\csc \theta as 1sinθ\frac{1}{\sin \theta}.
  2. Rewrite cotθ\cot \theta as cosθsinθ\frac{\cos \theta}{\sin \theta}.

This gives us: 1sinθsinθ=cosθsinθcosθ\frac{1}{\sin \theta} - \sin \theta = \frac{\cos \theta}{\sin \theta} \cdot \cos \theta

Step 2: Simplify the Left Side

The left side becomes: 1sinθsinθ=1sin2θsinθ\frac{1}{\sin \theta} - \sin \theta = \frac{1 - \sin^2 \theta}{\sin \theta}

Using the Pythagorean identity, 1sin2θ=cos2θ1 - \sin^2 \theta = \cos^2 \theta, this simplifies to: cos2θsinθ\frac{\cos^2 \theta}{\sin \theta}

Step 3: Simplify the Right Side

The right side is: cosθsinθcosθ=cos2θsinθ\frac{\cos \theta}{\sin \theta} \cdot \cos \theta = \frac{\cos^2 \theta}{\sin \theta}

Step 4: Conclusion

Both sides are equal: cos2θsinθ=cos2θsinθ\frac{\cos^2 \theta}{\sin \theta} = \frac{\cos^2 \theta}{\sin \theta}

Thus, the original equation holds: cscθsinθ=cotθcosθ\csc \theta - \sin \theta = \cot \theta \cos \theta

Would you like further clarification on any steps?


Here are five related questions to explore:

  1. How can we derive other trigonometric identities from basic identities like sin2θ+cos2θ=1\sin^2 \theta + \cos^2 \theta = 1?
  2. What are the proofs for other fundamental trigonometric identities?
  3. How do reciprocal identities relate to trigonometric simplifications?
  4. Can you solve equations involving mixed trigonometric terms (like sinθ+cosθ\sin \theta + \cos \theta)?
  5. How do transformations of trigonometric functions affect their graphs?

Tip: When working with trigonometric identities, converting terms to sine and cosine is often helpful for simplification.

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Math Problem Analysis

Mathematical Concepts

Trigonometry
Trigonometric Identities
Reciprocal Identities
Pythagorean Identities

Formulas

csc θ = 1 / sin θ
cot θ = cos θ / sin θ
Pythagorean identity: sin^2 θ + cos^2 θ = 1

Theorems

Pythagorean Identity

Suitable Grade Level

Grades 10-12