Question

(1+ctg бета)^2+(1-ctg бета)^2

Answer 1

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