$\"\"$

The expression is $\"\"$ .

$\"\"$ (Apply pythagorean identity)

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

$\"\"$ (Evaluate power: $\"\"$ ) $\"\"$

$\"\"$ (Add: 4 + 1 = 5)

$\"\"$ (Take the square root of each side)

$\"\"$ (Simplify)

$\"\"$ is in the second quadrant, sec $\"\"$ is negative,

Therefore $\"\"$ . $\"\"$

The value of $\"\"$ .