Question

5sin²x+4sin(П2+x)=4 срочно помогите

Answer 1

5sin^2x+4cosx=4
5-5cos^2x+4cosx=4
5cos^2x-4cosx-1=0
a=cosx
5a^2-4a-1=0
D=36
a1=(4+6)/10=1,cosx=1,x=2Пn
a2=(4-6)/10=-0,2;cosx=+-(П-arccos0,2+2Пn)