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TopNewestIt will help others if you provide some context to this. I believe that you are referring to the problem, in which we used the "CAST rule" in trigonometry. It is a simple mnemonic that helps students remember which of the trigonometric functions are positive in which quadrant. If you mark it out, you get

\[ \begin{array} { c | c} \sin & \mbox{All} \\ \hline \tan & \cos \\ \end{array} \]

Cosine is positive in the fourth quadrant,

All of them are positive in the first quadrant,

Sine is positive in the second quadrant,

Tangent is positive in the third quadrant.

This forms CAST.

There are other ways of using a mnemonic. Personally, I prefer to remember it as "A-S-T-C". You can form your own sentence with those letters in order, like "All Students Teach Calculus". – Calvin Lin Staff · 4 years ago

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– Shourya Pandey · 4 years ago

even i remember it by a-s-t-c ;" All school to college!"Log in to reply

– Markjames Laraga · 4 years ago

Cat rule ahh CoolLog in to reply

– Markjames Laraga · 4 years ago

I mean castLog in to reply

CAST rule – Lingaiah Vallakatla · 4 years ago

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