Объяснение:
164. (1+ctg²α)sin²α+1=(1+cos²α/sin²α)sin²α+1=sin²α+cos²α+1=1+1=2.
165. (tgα*ctgα-cos²α)/sin²α=(1-cos²α)/sin²α=sin²α/sin²α=1.
166. tgα*ctgα+sinα=1+sinα.
