Similarity
Ratios and Proportions
Similar Polygons

The Golden Ratio = 1.618

ie. the long side is 1.618 times longer than the short side

Proving Triangles Similar
Similarity in Right Triangles
Altitude Theorem
Proportions in Triangles

Angle Bisector Theorem

Side Splitter Theorem

Perimeter and Areas of Similar Figure
Proportionality and Area