13/30 -2/45 = 39/90 - 4/90 = 35/90 = 7/18
Все числа на листке...............................
18,3*0,3=5,48, всё просто
Cosα = 1/2*√2(1 + √3/2)
Cosα = 1/2*√4*1/2*(1 + Сosπ/6)
Cosα= 1/2 * 2 *√1/2*(1 + Cosπ/6)
Cosα = √ 1/2*(1 + Cosπ/6)
α = π/12
<span>(4 5/6 - 2,5) * 12 - 27 * 5/9 = 43
1) 4 5/6 - 2,5 = 29/6 - 25/10 = (5*29 - 3*25)/30 = (145 - 75)/30 = 70/30= 7/3
2) 7/3 * 12 = 28
3) 27 * 5/9 = 15
4) 28 + 15 = 43
(2 7/12 + 1,75) : 13 + 2,5 : 3 3/4= 1
1) 2 7/12 + 1,75 = 31/12 + 175/100 = 31/12 + 7/4 = (31+21)/12 = 52/12= 13/3
2) 13/3 : 13 = 13/3 * 1/13 = 1/3
3) 2,5 : 3 3/4 = 25/10 : 15/4 = 25/10 * 4/15 = 2/3
4) 1/3 + 2/3 = 3/3 = 1</span>