$\"\"$

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Observe the figure, the angle is $\"\"$ in right triangle and its adjacent side is 4 and opposite side is 3.

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$\"\"$ (Write Pythagorean theorem)

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Apply rule of exponents)

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$\"\"$ (Simplify)

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$\"\"$ (Apply square root each side)

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The trigonometric function is $\"\"$ . $\"\"$

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$\"\"$ (Write trigonometric function)

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$\"\"$ (Apply double angle formula: $\"\"$ )

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$\"\"$ (Substitute $\"\"$ )

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$\"\"$ (Apply rule of exponents)

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$\"\"$ (Apply LCM rule: $\"\"$ )

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$\"\"$ (Simplify) $\"\"$

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The solutions are $\"\"$ .