1) -4+(-7) = -11
2) -0,46+(-0,89) = -1,35
3) -2,3+(-0,86) = -3,16
4) -5 7/9 + (-3 4/9) = -52/9 + (-31/9) = (-52-31) / 9 = -83/9 = - 9 2/9
5) - 5/8 + (-11/12) = (-15-22) / 24 = -37/24 = - 1 13/24
6) -4 5/14+(-7 9/21)=-61/14 + (-156/21) = (-1281-2184) / 294 =-3465/294 =-11 231/294
1) 1 км/мин х 60 мин=60км\ч
2)60км\ч х 5 ч=300км
Ответ 300 км
8 · 4 = 32 (л) 8 ·6 = 48 (л) 8 ·7 = 56 (л) 8 ·9 = 72 (л)
Cosa=-5/13
sina=-√(1-cos²a)=-√(1-25/169)=-√(144/169)=-12/13
ctga=cosa/sina=-5/13:(-12/13)=5/13*13/12=5/12
cos²a/2=(1+cosa)/2=(1-5/13)/2=8/13:2=4/13
cosa/2=+-2/√13