При х = 6
4/18 = 9 - 1/12
4/18 = 8/12
1/9 = 4/3
при х = 8
4/24 = 9 -1/16
4/24 = 8/16
1/3 = 1/4
3/2 - 9/5 = 15/10 - 18/10 = - 3/10 = - 0,3
(19/8 + 11/12)/5/48 = 31 3/5
1) 19/8 + 11/12 = 57/24 + 22/24 = 79/24
2) 79/24 : 5/48 = 79/24 * 48/5 = 158/5 = 31 3/5 = 31,6
1. /_С= 180-(10+20)=150
По следствию из теоремы синусов
АВ/sin150=2R
sin150=sin30=1/2
1/(1/2)=2R
2=2R
R=1.
2. По теореме косинусов
a^2=b^2+c^2-2*b*c*cos/_(b;c)
cos120= -cos60= -1/2
a^2=9+25-2*3*5*(-1/2)
a^2=9+25+15=49
a=7