When You Know 2 Sides and 1 Angle \begin{equation*} A=\frac{1}{2} b c \sin \alpha \end{equation*} When You Know 1 Side and 2 Angles...
Law of Sines Consider this triangle. Draw a line vertically down from \(B\). Label the length of this line as \(h\) (for height). Now...
Formula for \(\cos(\alpha-\beta)\) Consider the unit circle below: Here, we make \(\overline{AB}=\overline{CD}\), so they have the...