Question

trigonométria (2.senx+1).(2.senx -1)=0

Answer 1

Lembrete:

⇒ $\left(a+b\right)\cdot \left(a-b\right)=a^2-b^2$
--------------------------------------------------
$\left(2sen\left(x\right)+1\right)\cdot \left(2sen\left(x\right)-1\right)\\\left(2sen\left(x\right)\right)^2-1^2\\2^2sen^2\left(x\right)-1\\\boxed{\bold{4sen^2\left(x\right)-1}}$