Author name: Ignatius

\(\color{blue} 2\sin \text {A} \cos \text {B} = \sin (\text{A + B}) + \sin (\text{A − B})\)   \(\color{blue} 2\cos […]

Soal 1 \(\cos \alpha + \cos (\alpha + 120^{\circ}) + \cos (\alpha + 240^{\circ}) = \dotso\) (A)  0 (B)  1

\(\color{blue}\sin\text{A} + \sin \text{B} = 2\sin\dfrac{1}{2}\text{(A + B)}\cos \dfrac{1}{2}\text{(A − B)}\)   \(\color{blue}\sin\text{A} \:-\: \sin\text{B} = 2\cos\dfrac{1}{2}\text{(A + B)}\sin \dfrac{1}{2}\text{(A

Soal 1 Jika \(\tan 40^{\circ} = \text{k}\), maka\(\dfrac{2\sin 20^{\circ} \cos 20^{\circ}}{2\:-\:4\cos^2 20^{\circ}} = \dotso\) (A)  \(-\dfrac{1}{4}\text{k}\) (B)  \(-\dfrac{1}{2}\text{k}\) (C)  \(\dfrac{1}{2}\text{k}\)

\(\color{blue}\sin \text{2A} = 2\sin \text{A} \cos \text {A}\)   \(\color{blue}\cos \text{2A} = \cos^2 \text{A} \:-\:\sin^2 \text{A}\) \(\color{blue}\cos \text{2A} = 1

Soal 1 Nilai \(\cos 15^{\circ} = \dotso\) (A)  \(\dfrac{1}{2}(\sqrt{3} + \sqrt{2})\) (B)  \(\dfrac{1}{4}(\sqrt{6} \:-\: \sqrt{2})\) (C)  \(\dfrac{1}{4}(\sqrt{6} + \sqrt{2})\) (D) 

\(\color{blue} \sin (\text{A + B}) = \sin \text{A}\cos \text{B} + \cos \text{A} \sin \text{B}\) \(\color{blue} \sin (\text{A − B}) =