Question

why primary colours are primary?

Answer 1

Primary colours are primary becuse these colours when mixed with each other in constant proportions  ...leads to formation of various colours.

Answer 2

The primary colors are those which cannot be created by mixing other colors in a givencolor space. For subtractive combination of colors, as in mixing of pigments or dyes for printing, the primaries normally used are cyan, magenta, and yellow, though the set of red, yellow, blue is popular among artists..............
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