understand the relationship of the secant, cosecant and cotangent
functions to cosine, sine and tangent, and use properties and graphs of all six trigonometric functions for angles of any magnitude;
• use trigonometrical identities for the simplification and exact
evaluation of expressions and in the course of solving equations, and select an identity or identities appropriate to the context, showing familiarity in particular with the use of:
sec^2(θ) ≡ 1 + tan^2(θ) and
cosec^2θ ≡ 1 + cot^2θ ,