Simplify the following expression:

[tex]\[ (\sin A + \operatorname{cosec} A)^2 + (\cos A + \sec A)^2 = \tan^2 A + \cot^2 A + 7 \][/tex]



Answer :

To solve the given equation [tex]\((\sin A + \csc A)^2 + (\cos A + \sec A)^2 = \tan^2 A + \cot^2 A + 7\)[/tex], let's break it down step by step and verify if both sides are indeed equal.

### Step 1: Simplify the Left-Hand Side (LHS)
We start with the expression on the left-hand side of the equation:

[tex]\[ (\sin A + \csc A)^2 + (\cos A + \sec A)^2 \][/tex]

First, expand each square term:

[tex]\[ (\sin A + \csc A)^2 = \sin^2 A + 2\sin A \cdot \csc A + \csc^2 A \][/tex]
[tex]\[ (\cos A + \sec A)^2 = \cos^2 A + 2\cos A \cdot \sec A + \sec^2 A \][/tex]

Since [tex]\(\csc A = \frac{1}{\sin A}\)[/tex] and [tex]\(\sec A = \frac{1}{\cos A}\)[/tex], we have:

[tex]\[ \sin A \cdot \csc A = \sin A \cdot \frac{1}{\sin A} = 1 \][/tex]
[tex]\[ \cos A \cdot \sec A = \cos A \cdot \frac{1}{\cos A} = 1 \][/tex]

Substituting these into the expanded form gives:

[tex]\[ (\sin^2 A + 2 \cdot 1 + \frac{1}{\sin^2 A}) + (\cos^2 A + 2 \cdot 1 + \frac{1}{\cos^2 A}) \][/tex]

Combine the terms:

[tex]\[ \sin^2 A + \csc^2 A + 2 + \cos^2 A + \sec^2 A + 2 \][/tex]

Since [tex]\(\csc^2 A = 1 + \cot^2 A\)[/tex] and [tex]\(\sec^2 A = 1 + \tan^2 A\)[/tex], substitute these identities:

[tex]\[ \sin^2 A + (1 + \cot^2 A) + 2 + \cos^2 A + (1 + \tan^2 A) + 2 \][/tex]

Simplify the expression:

[tex]\[ \sin^2 A + \cos^2 A + \cot^2 A + \tan^2 A + 1 + 1 + 2 + 2 \][/tex]

Using the Pythagorean identity [tex]\(\sin^2 A + \cos^2 A = 1\)[/tex], we get:

[tex]\[ 1 + \cot^2 A + \tan^2 A + 6 \][/tex]

So, the simplified form of the left-hand side is:

[tex]\[ \tan^2 A + \cot^2 A + 7 \][/tex]

### Step 2: Simplify the Right-Hand Side (RHS)
We take the expression on the right-hand side of the equation, which is already simplified:

[tex]\[ \tan^2 A + \cot^2 A + 7 \][/tex]

### Step 3: Compare LHS and RHS
Notice that both sides of the equation are already in the same simplified form:

[tex]\[ \tan^2 A + \cot^2 A + 7 \][/tex]

### Conclusion
Since the left-hand side simplifies to exactly the same form as the right-hand side, we can conclude that the given equation holds true.

Therefore:

[tex]\[ (\sin A + \csc A)^2 + (\cos A + \sec A)^2 = \tan^2 A + \cot^2 A + 7 \][/tex]

Thus, the equation is correct and verified.