Using eulers formulas to obtain trigonometric identities in

Question

Using Euler's Formulas to Obtain Trigonometric Identities. In this lesson, we will explore the derivation of several trigonometric identities, namely

cos(x + y) = cosxcosy- sinxsiny

and sin(x + y) = sinxcosy+ sinycosx

also

cos2x = cos²x- sin²x

along with sin2x = 2sinxcosx

and lastly, DeMoivre's Formula,

(cosx+ isinx)ⁿ = cosnx+ isinnx

Using Euler's Formula. To get a good understanding of what is going on, you will need a previous knowlege of series expansions and complex numbers! This article will provide avery little explanation of these subjects, so you may want to refresh your knowledge first