1) -2cosx * sinx = sin 2x
2) 2 sinx*cosx-2cosx*sinx=0
√32 - √128sin²(9π/8) = √32(1 - 2sin²π/8) = √32(cos2π/8) = 4√2*cos(π/4) =
= 4√2*(√2/2) = 4
(3(a-2b)^2)/(a-2b)(a+2b) = 3(a-2b)/(a+2b)
(a-2)^2/b(b^2+1)*(b^2+1)/(2-a) = -(a-2)/b
Sin^2Pi/8 + 2cosPi/8sinPi/8 + cos^2Pi/8 - 2cosPi/8sinPi/8 = sin^2Pi/8 + cos^2Pi/8 = 1