Trigonometry
10
11.1 Introduction
EMCCE
In this chapter we will build on the trigonometryfrom previous years by looking at the result applying
trigonometric functionsto sums and differencesof angles. We will alsoapply trigonometry to solving
geometric problems in two and three dimensions.
See introductory video:VMhtu at http://www.everythingmaths.co.za
10.2 Compound AngleIdentities EMCCF
Derivation ofsin(α+β) EMCCG
We have, for any angles α and β, that
sin(α +β) = sinα cosβ + sinβ cosα
How do we derive this identity? It is tricky, so follow closely.
Suppose we have the unit circle shown below. The two points L(a;b) and K(x;y) are on the circle.