Make the Indicated Trigonometric Substitution in the Given Algebraic Expression $0 \leq x \leq \pi / 2$

Short Answer

Make the indicated trigonometric substitution in the given algebraic expression and simplify.Assume that $0 \leq x \leq \pi / 2$
$\sqrt { x ^ { 2 } - 4 } , \quad x = 2 \sec \theta$