Answer :

Sure, let's solve the equation [tex]\(1 - \sin \theta \cdot \cos \theta \cdot \tan \theta = \cos^2 \theta\)[/tex] step by step.

1. Start with the given equation:
[tex]\[ 1 - \sin \theta \cdot \cos \theta \cdot \tan \theta = \cos^2 \theta \][/tex]

2. Use the definition of the tangent function:
[tex]\[ \tan \theta = \frac{\sin \theta}{\cos \theta} \][/tex]

3. Substitute the definition of [tex]\(\tan \theta\)[/tex] into the equation:
[tex]\[ 1 - \sin \theta \cdot \cos \theta \cdot \frac{\sin \theta}{\cos \theta} = \cos^2 \theta \][/tex]

4. Simplify the expression:
[tex]\[ 1 - \sin \theta \cdot \sin \theta = \cos^2 \theta \][/tex]

5. Combine the [tex]\(\sin^2 \theta\)[/tex] terms:
[tex]\[ 1 - \sin^2 \theta = \cos^2 \theta \][/tex]

6. Recall the Pythagorean identity:
[tex]\[ \sin^2 \theta + \cos^2 \theta = 1 \][/tex]

7. Using the Pythagorean identity, rewrite [tex]\(1 - \sin^2 \theta\)[/tex]:
[tex]\[ 1 - \sin^2 \theta = \cos^2 \theta \][/tex]

8. Thus, the equation simplifies to:
[tex]\[ \cos^2 \theta = \cos^2 \theta \][/tex]

We've shown through these steps that:
[tex]\[ 1 - \sin \theta \cdot \cos \theta \cdot \tan \theta = \cos^2 \theta \][/tex]
holds true for all [tex]\(\theta\)[/tex].