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Solve the equation:

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


Sagot :

Alright, let's proceed with the given equation step-by-step to prove that it is correct.

We start with the given expression:
[tex]\[ \frac{1 - \cos(2A)}{2 \cos(A)} = \sin(A) \tan(A) \][/tex]

First, let's simplify the left-hand side (LHS) of the equation:
[tex]\[ \frac{1 - \cos(2A)}{2 \cos(A)} \][/tex]

To simplify this, we use a trigonometric identity for [tex]\(\cos(2A)\)[/tex]:
[tex]\[ \cos(2A) = 1 - 2 \sin^2(A) \][/tex]

Substitute this identity into the LHS:
[tex]\[ 1 - \cos(2A) = 1 - (1 - 2 \sin^2(A)) = 1 - 1 + 2 \sin^2(A) = 2 \sin^2(A) \][/tex]

Now, substitute [tex]\(1 - \cos(2A)\)[/tex] in the LHS:
[tex]\[ \frac{2 \sin^2(A)}{2 \cos(A)} \][/tex]

Simplify the fraction:
[tex]\[ \frac{2 \sin^2(A)}{2 \cos(A)} = \frac{\sin^2(A)}{\cos(A)} \][/tex]

So, the simplified LHS is:
[tex]\[ \frac{\sin^2(A)}{\cos(A)} \][/tex]

Next, let's simplify the right-hand side (RHS) of the equation:
[tex]\[ \sin(A) \tan(A) \][/tex]

Using the definition of [tex]\(\tan(A)\)[/tex]:
[tex]\[ \tan(A) = \frac{\sin(A)}{\cos(A)} \][/tex]

Substitute this into the RHS:
[tex]\[ \sin(A) \tan(A) = \sin(A) \left(\frac{\sin(A)}{\cos(A)}\right) = \frac{\sin^2(A)}{\cos(A)} \][/tex]

So, the simplified RHS is:
[tex]\[ \frac{\sin^2(A)}{\cos(A)} \][/tex]

Both the simplified LHS and RHS are:
[tex]\[ \frac{\sin^2(A)}{\cos(A)} \][/tex]

Therefore, the original equation is verified:
[tex]\[ \frac{1 - \cos(2A)}{2 \cos(A)} = \sin(A) \tan(A) \][/tex]

This confirms that the given equation holds true.