Respuesta :
Answer:
Think of the double angle formula for
sin
2
x
Explanation:
sin
2
x
=
sin
x
2
sin
x
cos
x
=
sin
x
2
sin
x
cos
x
−
sin
x
=
0
sin
x
(
2
cos
x
−
1
)
=
0
Solution A:
sin
x
=
0
⇒
x
=
k
π
,
k
∈
Z
Solution B:
2
cos
x
=
1
⇒
cos
x
=
1
2
,
x
=
±
π
3
+
2
k
π
=
π
3
(
6
k
±
1
)
,
k
∈
Z
∴
x
=
k
π
or
x
=
π
3
(
6
k
±
1
)
,
k
∈
Z
Step-by-step explanation:
Answer:
[tex]\bold{x=\frac\pi3+2k\pi\quad \vee\quad x=\frac{5\pi}3+2k\pi\quad \vee\quad x=k\pi\ ,\quad k\in\mathbb Z}[/tex]
Step-by-step explanation:
[tex]\sin 2x=\sin x\\\\\sin2x - \sin x=0\\\\2\sin x\cos x-\sin x=0\\\\(2\cos x-1)\sin x=0\\\\2\cos x-1=0\qquad\qquad\qquad\qquad or\qquad \sin x=0\\\\2\cos x=1\quad\qquad\qquad\qquad\qquad\ or\qquad \sin x=0\\\\\cos x=\frac12\qquad\qquad\qquad\qquad\qquad or\qquad \sin x=0\\\\x=\frac\pi3+2k\pi\quad \vee\ \ x=\frac{5\pi}3+2k\pi\quad\ \ \vee\ \ x=0+k\pi\ ,\quad k\in\mathbb Z[/tex]