Question
Establish the identity. \[ (\csc \theta+\cot \theta)(\csc \theta-\cot \theta)=1 \] Multiply and write the left side expression as the difference of two squares.
Ask by Robbins Ramos. in the United States
Jan 23,2025
Real Tutor Solution
Tutor-Verified Answer
Answer
\[
\csc^2 \theta - \cot^2 \theta = 1
\]
Solution
Calculate or simplify the expression \( (\csc \theta+\cot \theta)(\csc \theta-\cot \theta) \).
Simplify the expression by following steps:
- step0: Solution:
\(\left(\csc\left(\theta \right)+\cot\left(\theta \right)\right)\left(\csc\left(\theta \right)-\cot\left(\theta \right)\right)\)
- step1: Transform the expression:
\(\frac{1+\cot\left(\theta \right)\sin\left(\theta \right)}{\sin\left(\theta \right)}\times \left(\csc\left(\theta \right)-\cot\left(\theta \right)\right)\)
- step2: Transform the expression:
\(\frac{1+\cot\left(\theta \right)\sin\left(\theta \right)}{\sin\left(\theta \right)}\times \frac{1-\cot\left(\theta \right)\sin\left(\theta \right)}{\sin\left(\theta \right)}\)
- step3: Multiply the terms:
\(\frac{\left(1+\cot\left(\theta \right)\sin\left(\theta \right)\right)\left(1-\cot\left(\theta \right)\sin\left(\theta \right)\right)}{\sin\left(\theta \right)\sin\left(\theta \right)}\)
- step4: Multiply the terms:
\(\frac{\left(1+\cot\left(\theta \right)\sin\left(\theta \right)\right)\left(1-\cot\left(\theta \right)\sin\left(\theta \right)\right)}{\sin^{2}\left(\theta \right)}\)
- step5: Transform the expression:
\(\frac{\left(1+\cos\left(\theta \right)\right)\left(1-\cos\left(\theta \right)\right)}{\sin^{2}\left(\theta \right)}\)
- step6: Transform the expression:
\(\frac{-\left(-\sin^{2}\left(\theta \right)\right)}{\sin^{2}\left(\theta \right)}\)
- step7: Calculate:
\(\frac{\sin^{2}\left(\theta \right)}{\sin^{2}\left(\theta \right)}\)
- step8: Reduce the fraction:
\(1\)
The identity \((\csc \theta + \cot \theta)(\csc \theta - \cot \theta) = 1\) is established.
Now, let's simplify the left side expression by multiplying it:
\((\csc \theta + \cot \theta)(\csc \theta - \cot \theta) = \csc^2 \theta - \cot^2 \theta\)
Therefore, the identity can be written as:
\(\csc^2 \theta - \cot^2 \theta = 1\)
Reviewed and approved by the UpStudy tutoring team
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Beyond the Answer
To establish the identity, we start by noting that the left-hand side can be expressed as the difference of two squares: \[ (\csc \theta + \cot \theta)(\csc \theta - \cot \theta) = \csc^2 \theta - \cot^2 \theta. \] Using the Pythagorean identity, we know that: \[ \csc^2 \theta = 1 + \cot^2 \theta. \] Now, substituting this into our expression gives: \[ \csc^2 \theta - \cot^2 \theta = (1 + \cot^2 \theta) - \cot^2 \theta = 1. \] Thus, we have shown that: \[ (\csc \theta + \cot \theta)(\csc \theta - \cot \theta) = 1. \] This confirms the identity is true!