Question

1-cosB/1+cosB - 1-2cosB/sin²B упростите

Answer 1

$displaystyle frac{1-cos beta }{1+cosbeta}- frac{1-2cosbeta}{sin^2beta}= frac{1-cosbeta}{1+cosbeta}- frac{1-2cosbeta}{(1-cosbeta)(1+cos beta)}=\ \ \ = frac{(1-cosbeta)^2-1+2cosbeta}{sin^2beta} = frac{1-2cosbeta+cos^2beta-1+2cosbeta}{sin^2beta} =ctg^2beta$