Geometry

• Sine rule:

  $\frac{\sin A}{a}$ = $\frac{\sin B}{b}$ = $\frac{\sin C}{c}$

  and the same applies flipped over

  
• Area of a triangle:

  $\frac{1}{2}ab\sin C$

  
• Arc length: $r\theta$

  
• Sector area: $\frac{1}{2}r^2\theta$

  
• Segment area: $\frac{1}{2}r^2\left(\theta-\sin\theta\right)$