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Simplify completely into an expression with [tex] \sin (A) [/tex] or [tex] \cos (A) [/tex] only:

[tex] \sin (A) \tan (A) + \cos (A) = \square \]


Sagot :

To simplify the expression [tex]\(\sin(A) \tan(A) + \cos(A)\)[/tex] into an expression involving only [tex]\(\sin(A)\)[/tex] or [tex]\(\cos(A)\)[/tex], we can follow these steps:

1. Recall the trigonometric identity for [tex]\(\tan(A)\)[/tex]:
[tex]\[ \tan(A) = \frac{\sin(A)}{\cos(A)} \][/tex]

2. Substitute [tex]\(\tan(A)\)[/tex] into the given expression:
[tex]\[ \sin(A) \tan(A) + \cos(A) = \sin(A) \left( \frac{\sin(A)}{\cos(A)} \right) + \cos(A) \][/tex]

3. Simplify the first term:
[tex]\[ \sin(A) \left( \frac{\sin(A)}{\cos(A)} \right) = \frac{\sin^2(A)}{\cos(A)} \][/tex]

4. So the expression now is:
[tex]\[ \frac{\sin^2(A)}{\cos(A)} + \cos(A) \][/tex]

5. To combine these terms, we need a common denominator:
[tex]\[ \frac{\sin^2(A)}{\cos(A)} + \frac{\cos^2(A)}{\cos(A)} \][/tex]

6. Combine the fractions:
[tex]\[ \frac{\sin^2(A) + \cos^2(A)}{\cos(A)} \][/tex]

7. Use the Pythagorean identity, which states that:
[tex]\[ \sin^2(A) + \cos^2(A) = 1 \][/tex]

8. Substitute [tex]\(1\)[/tex] for [tex]\(\sin^2(A) + \cos^2(A)\)[/tex] in the expression:
[tex]\[ \frac{1}{\cos(A)} \][/tex]

Thus, the simplified expression is:
[tex]\[ \frac{1}{\cos(A)} \][/tex]