Question

(1+ctgx)^2- 1/sin^2 x помогите упростить плиз

Answer 1

(1+ctgx)² - 1/sin²x = 1+2ctgx+ctg²x-1/sin²x=(1+ctg²x)+2cgx - 1/sin²x = 
1/sin²x+2ctgx-1/sin²x = 2ctgx.