Math Visual Infographic

Please create a mathematical visual infographic about "{argument name="knowledge point" default="mathematical concept/knowledge point"}', aiming to help readers intuitively understand: what it is, why it holds, what geometry/structural intuition is, and how it performs in different scenarios. The image should look like a high-quality math handout + hand-drawn educational poster—elegant, clear, and informative, but not cluttered. 

Visual style: {argument name="Image ratio" default="Vertical or landscape is fine"}, clean light-colored paper background, dark blue title, black/dark gray body lines, paired with a small amount of elegant blue, teal, gold, and red accent colors. Use rounded cards, fine line borders, numbering labels, hand-drawn arrows, local magnification boxes, and summary bars. The overall design should be aesthetically pleasing, balanced, and academic, making the concept's "structure" and "why" immediately clear.