(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
2ctgB* 2tgB=4
4ctgB* tgB=4
4*1=4
4=4 теперь мине помоги