Trigonometric identity: |

The denominator can be simplified by applying the identity (a + b)(a - b) = a

^{2}- b

^{2},

From the identity sin

^{2}θ + cos

^{2}θ = 1, it follows that cos

^{2}θ = 1 - sin

^{2}θ,

Square roots and powers of 2 cancel each other out,

Distributing the denominator in the numerator,

Applying [ 1 / cos θ = sec θ ] and [ sin θ / cos θ = tan θ ],

sec θ + tan θ

... which is the right hand side expression

Trigonometric identities applied:

- sin
^{2}θ + cos^{2}θ = 1 - 1 / cos θ = sec θ
- sin θ / cos θ = tan θ