Why is θ used to represent an unknown angle in plane geometry?
Mathematical symbols all have histories behind them. I know that it's not all the important what symbol is used to represent an unknown angle, but I am very interested in why θ in particular seems to be universally used.
I've heard a lot of different stories as to why this is, but I've gotten no firm reference to an early mathematics book, a linguistic reason, or anything else.
Please help! I want to make the math tutorials I am putting together have something about the symbols involved, and this is the only one I couldn't find details on.
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From what I have learned in my math classes, theta, phi, and other Greek symbols are used to represent an unknown angle in plane geometry in the same way as x and y are used to to represent unknown numbers in algebra. Theta is treated similarly to x BECAUSE it is universally accepted. I don't believe there is another sure reason why it is used. Why is x used in algebra? If you know the answer to that, it is most likely the answer to your question.
I was just looking up the same question for the same reason as Sean. I agree that, sure, they're just using random letters, but why theta? And it just occurred to me that in the Greek alphabet, theta is the 4th letter of a triangle.
If they drew triangles the same way we do, then the vertices would be A,B,C (alpha, beta, gamma, in Greek). If you wanted a separate name for the angle measure at vertex A, then the next letter in the Greek alphabet would be theta. Even if it was an Arab working the trigonometric value of taking angle measures, he might do his notes and numbers in Arabic script, and his labels, still based on Greek-developed concepts, in the Greek alphabet.
Anyone have access to original texts?
Angle Symbol In Trig
a pal despatched me that one alongside with various different questions he stumbled on someplace. Heres 2 samples: a million) If flying is so secure, why do they call the airport the terminal? 2) Why is it that docs call what they do 'prepare'? i imagine the actual answer to the question you requested is because the metallic used in planes at present is different then the black container metallic. The metallic that is used in planes is lighter and can want to enhance and flex, a sturdy non versatile metallic if used in planes might want to nonetheless reason the airplane to tear itself up simply by intense wind and rigidity the planes are subjected to creating it better weak than it already is.
I don't know exactly where it came from but my math teacher a long time ago said that trigonometry was mostly an Arabic discovery so you could find something of relevance there