$\"\"$

The trigonometric equation is $\"italic$ .

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

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

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

$\"begin$

$\"\"$

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

$\"begin$

x = 4 (x > 0)

Then $\"italic$ . $\"\"$

a) $\"italic$

Apply double-angle formula: $\"italic$ .

$\"equal$ (Substitute $\"italic$ )

$\"equal$

$\"\"$

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