$\"\"$

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The trigonometric expression is $\"italic$ .

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$\"italic$ , let $\"begin$ and place $\"begin$ in quadrant I.

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The point P = (x, y) = (x, 3) = x > 0 is on a circle of radius, $\"begin$ .

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

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

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$\"begin$ (Subtract 9 from each side)

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$\"begin$ (Simplify)

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$\"begin$ (Simplify)

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$\"begin$ (x > 0)

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$\"italic$ (Substitute $\"begin$ , r = 5) $\"\"$

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$\"begin$ , let $\"begin$ and place $\"begin$ in quadrant II.

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The point P = (x, y) = $\"begin$ = y < 0 is on a circle of radius, $\"begin$ .

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

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

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$\"Syntax$ (Subtract 20 from each side)

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$\"begin$ (Simplify)

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$\"begin$ (y < 0)

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$\"italic$ (Substitute $\"begin$ , r = 5) $\"\"$

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a) $\"italic$

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The sum formula for the sine function: $\"italic$ .

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Substitute $\"italic$ .

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$\"equal$

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$\"equal$ (Simplify)

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$\"equal$ (Rewrite the expression with common denominator)

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$\"equal$ (Take out common term $\"begin$ )

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

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The value of $\"italic$ $\"equal$ .