2ab a-b 2ab+(a-b)(a-b) 2ab+(a-b)²
------------------------ + ----------------- = ------------------------ = -------------------- =
(a-b)( a²+ab+b²) a²+ab+b² (a-b)( a²+ab+b²) (a-b)( a²+ab+b²)
2ab+a²-2ab+b² a²+b² (a-b)(a+b) a+b
= ----------------------- = --------------------- = --------------------- = ----------------
(a-b)( a²+ab+b²) (a-b)( a²+ab+b²) (a-b)( a²+ab+b²) ( a²+ab+b²)
В знаменателе имеем sin^2 11+cos^2 11 = 1. 34/1=34
Ответ: 34.
1) x-y=2
x^2-xy+y^2=7
x=2+y
(2+y)^2 - y(2+y)+y^2=7
y^2+2y+4=7
y^2+2y-3+0
D=4-4*(-3)=16
y1 = -2+4/2 =1
y2 = -2-4/2 = -3
x1 = 2+1= 3
x2 = 2-3= -1
Ctg(x/2 + π/8) = √3
x/2 + π/8 = π/6 + πk, k∈Z
x/2 = π/6 - π/8 + πk = π/24 + πk, k∈Z
x = π/12 + 2πk, k∈Z