Question

Ребята помогите плиз) 5sin2x+4sin(п/2+x)=4

Answer 1

5sin^2x+4sin(п/2+x)=4
5sin^2x + 4cosx = 4
5*(1 - cos^2x) + 4cosx - 4 = 0
5 - 5cos^2x + 4cosx - 4 = 0
5cos^2x - 4cosx - 1 =
D = 16 + 4*5*1 = 36
cosx = (4 -6)/10
cosx = - (1/5)
x1 = (+ -)arccos(-1/5) + 2πk, k∈Z
cosx = (4 + 6)/10
cosx = 1
x2 = 2πn, n∈Z