### Johnson's answer to alice's Secondary 4 A Maths Singapore question.

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Hope it helps

Date Posted:
5 months ago

Of course, not if you view it as cot theta = 1 / tan theta (at least for O Levels where they count tan pi/2 as “undefined”).

If you view it as cot theta = cos theta / sin theta and we realise that cos and sin of the angle cannot be zero at the same time (ie 0/0 is not possible) then cot theta = 0 leads to cos theta = 0.

With angles pi/2 and 3pi/2.