[tex]tg435+tg375=\frac[sin(435+375)]
{cos435
cos375}=\frac{sin810}{
cos435
cos375=\frac{90}{cos75
cos15}[\tex][tex]=\frac{1}{
cos75 cos15}=\frac{1}\frac{cos
(75-15)+cos(75+15)}{2}}=\frac{2}{cos60+cos90}=
\frac{2}{\frac{1}{2}+0}=4[\tex]
10ab+(-5a+b)² = 10ab +(b-5a)² = 10ab+ b² -10ab +25a² = b²+25a²
при a=√10 и b=√5 b²+25a²=(√5)²+25(√10)² = 5+25*10 =5+250=255