buktikan cos beta/1-tan beta + sin beta/1-cot beta =sin beta + cos beta

IDENTITAS TRIGONOMETRI

cos b/(1 - tan b) + sin b/(1 - cot b)
= cos² b /(cos b - sin b) + sin² b/(sin b - cos b)
= (cos² b - sin² b) / (cos b - sin b)
= (cos b + sin b)(cos b - sin b) / (cos b - sin b)
= cos b + sin b
_terbukti_