Trigonometric substitution

\(\sqrt{a^2-x^2}\).

\(\sqrt{a^2-x^2}\).

\(\sqrt{a^2-x^2}\).

\(\sqrt{a^2-x^2}\).

\(\sqrt{a^2-x^2}\).

\(\sqrt{a^2-x^2}\).

\(\sqrt{x^2+a^2}\).

\(\sqrt{x^2-a^2}\).