Question

Спростіть вираз
(1÷sina-ctga)(1÷sina+ctga)-1
СРОЧНО!!!

Answer 1

(1/sinα -ctgα)(1/sinα +ctgα) -1=
=(1/sinα-cosα/sinα)(1/sinα+cosα/sinα) -1=
=(1-cosα)(1+cosα)/sin²α -1=(1-cos²α)/sin²α -1=
=sin²α/sin²α -1=1-1=0