Question

4sin^2x + 11 sinx - 3=0

Answer 1

Пусть sinx =t ( |t|≤1)

4t²+11t-3=0
D=121+48=169; √D=13
t1=(-11-13)/8=-3 - ∅ [-1;1]
t2=(-11+13)/8=1/4

замена

sinx=1/4
x=(-1)^k *arcsin1/4+πk