tg30° × ctg60° + tg60° × ctg30° = 10/3
tg30° = √3/3
ctg60° = √3/3
tg60° = √3
ctg30° = √3
√3/3 × √3/3 + √3 × √3 = 9/3 + 3 = ( 1 + 9 )/3 = 10/3
