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Simplify the expression:

[tex]\[
\frac{\cos \theta}{1 - \sin \theta} - \frac{\cos \theta}{1 + \sin \theta} = 2 \tan \theta
\][/tex]


Sagot :

Let's solve the equation step by step:

[tex]\[\frac{\cos \theta}{1-\sin \theta}-\frac{\cos \theta}{1+\sin \theta}= 2 \tan \theta\][/tex]

Step 1: Find a common denominator for the left-hand side expressions.

The denominators are [tex]\(1 - \sin \theta\)[/tex] and [tex]\(1 + \sin \theta\)[/tex].

Common denominator = [tex]\((1 - \sin \theta)(1 + \sin \theta)\)[/tex]

Step 2: Rewrite the left-hand side with the common denominator

[tex]\[ \frac{\cos \theta (1 + \sin \theta)}{(1 - \sin \theta)(1 + \sin \theta)} - \frac{\cos \theta (1 - \sin \theta)}{(1 - \sin \theta)(1 + \sin \theta)} \][/tex]

Step 3: Simplify the numerators

[tex]\[ \frac{\cos \theta (1 + \sin \theta) - \cos \theta (1 - \sin \theta)}{(1 - \sin \theta)(1 + \sin \theta)} \][/tex]

[tex]\[ = \frac{\cos \theta (1 + \sin \theta) - \cos \theta (1 - \sin \theta)}{1 - \sin^2 \theta} \][/tex]

Step 4: Use the Pythagorean identity [tex]\(1 - \sin^2 \theta = \cos^2 \theta\)[/tex]

[tex]\[ = \frac{\cos \theta (1 + \sin \theta) - \cos \theta (1 - \sin \theta)}{\cos^2 \theta} \][/tex]

[tex]\[ = \frac{\cos \theta + \cos \theta \sin \theta - \cos \theta + \cos \theta \sin \theta}{\cos^2 \theta} \][/tex]

Step 5: Combine like terms in the numerator

[tex]\[ = \frac{2 \cos \theta \sin \theta}{\cos^2 \theta} \][/tex]

Step 6: Simplify the fraction

[tex]\[ = 2 \frac{\sin \theta}{\cos \theta} \][/tex]

[tex]\[ = 2 \tan \theta \][/tex]

Thus, we have shown that:

[tex]\[\frac{\cos \theta}{1-\sin \theta}-\frac{\cos \theta}{1+\sin \theta}= 2 \tan \theta\][/tex]

The initial equation is verified to be true. So, the given equation holds, and the solution is correct.