Practice question · Multiple choice
A search engine measures document similarity by the angle between vectors rather than the distance. Why is the angle the right choice?
Hints
- Take an article and the same article printed twice. Compare their vectors.
- Which measure calls those two documents identical, and which calls them far apart?
Show the answer
C. Because a long document has a larger vector on the same topic
Why
Doubling a document doubles its vector — same direction, twice the length — so distance says 'different' and the angle says 'identical', which is the answer anyone wants. Length here encodes verbosity rather than content, and cosine similarity is the decision to ignore it.
Practise Inner Product Spaces and Orthogonality
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