Respuesta :

we need to plug the function f(x) sin²x + sin(x) on the radical graph and see for which x it is when y is under 0, on the intervall 0<x<2pi

We see on the graf that sin²x+sinx < 0 on the interval: 0<x<2pi.

when:

pi<x<1.5pi

and:

1.5pi<x<2pi