1+2cosx+ cos²x sin³x
= ( ------------------------- +1) · -------------- =
sin²x 1+cosx
1+2cosx+cos²x+sin²x sin³x 2(1+cosx)·sin³x
= --------------------------------- · ----------------- = ---------------------------- =
sin²x 1+cosx sin²x·(1+cosx)
= 2sinx