Question

Вычислить
Tg2a+ctg2a если tga + ctga = 3

Answer 1

${rm tg}^2alpha+{rm ctg}^2alpha+2{rm tg}alpha{rm ctg}alpha-2{rm tg}alpha{rm ctg}alpha=({rm tg}alpha+{rm ctg}alpha)^2-2=3^2-2=7$