1)a^2×cos O°-2ab×sin 90°+t^2×tg^2 45 2)a^2×sin180°+2ab×cos90°+b^2×tg 45°
Cos0° = 1; sin90° = 1; tg²45° = 1 1) a² - 2ab + t² sin180° = 0; cos90° = 0; tg45° = 1 a²*0 + 2ab*0 + b² = b²