1. Right Triangles
   1. Ratios
      1. Cosine Ratio
      2. Sine Ratio
      3. Tangent Ratio
   2. Similar Triangles
      1. Definition: Identical Shape (same angles) different sizes.
      2. The scale factor (k) relates the lengths of corresponding sides of similar triangles.
         1. AB = k(PQ)
      3. The square of the scale factor relates the area of two similar triangles.
2. Acute Triangles
   1. Sine Law
   2. Cosine Law