Question

cos ² α+tg² α * ctg² α + sin²α=

Answer 1

cos²α + tg²αctg² + sin²α = 1 + 1 = 2

Answer 2

tgα * Ctgα = 1
Sin²α + Cos²α = 1

Cos²α + tg²α * Ctg²α + Sin²α = (Cos²α + Sin²α) + tg²α * Ctg²α = 1 + 1 = 2