(tgB+ctgB )^2-(TgB -ctgB )^2=4

Question

(tgB+ctgB )^2-(TgB -ctgB )^2=4

Answer 1

(tgB+ctgB )^²-(TgB -ctgB )²=4
(tgB+ctgB -(TgB -ctgB ))(tgB+ctgB +TgB -ctgB )=4
2сtgB*2tgB=4
4=4