Latihan Matematika Peminatan Kelas XII Nilai Limit Fungsi Trigonometri
# 4
Pilgan

Nilai dari limxπ33xsin(x π3)tan(12xπ6)\lim\limits_{x\to\frac{\pi}{3}}\frac{3x\sin\left(x-\ \frac{\pi}{3}\right)}{\tan\left(\frac{1}{2}x-\frac{\pi}{6}\right)} adalah ....

A

2π2\pi

B

12π\frac{1}{2}\pi

C

π\pi

D

13π\frac{1}{3}\pi

E

34π\frac{3}{4}\pi

Pembahasan:

Berdasarkan rumus umum limit fungsi trigonometri bahwa

limx0sinmxtannx=mn\lim\limits_{x\to 0}\frac{\sin mx}{\tan nx}=\frac{m}{n}

Dengan demikian,

limxπ33xsin(x π3)tan(12xπ6)\lim\limits_{x\to\frac{\pi}{3}}\frac{3x\sin\left(x-\ \frac{\pi}{3}\right)}{\tan\left(\frac{1}{2}x-\frac{\pi}{6}\right)} =limxπ33xsin(xπ3)tan12(xπ3)=\lim\limits_{x\to\frac{\pi}{3}}\frac{3x\sin\left(x-\frac{\pi}{3}\right)}{\tan\frac{1}{2}\left(x-\frac{\pi}{3}\right)}

=limxπ33x . limxπ3sin(xπ3)tan12(xπ3)=\lim\limits_{x\to\frac{\pi}{3}}3x\ .\ \lim\limits_{x\to\frac{\pi}{3}}\frac{\sin\left(x-\frac{\pi}{3}\right)}{\tan\frac{1}{2}\left(x-\frac{\pi}{3}\right)}

=limxπ33x . 112=\lim\limits_{x\to\frac{\pi}{3}}3x\ .\ \frac{1}{\frac{1}{2}}

=limxπ33x . 2=\lim\limits_{x\to\frac{\pi}{3}}3x\ .\ 2

Selanjutnya, substitusikan x=π3x=\frac{\pi}{3}

=3(π3) . 2=3\left(\frac{\pi}{3}\right)\ .\ 2

=2π=2\pi