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Mathematics 16 Online
OpenStudy (theislander):

what is the correct definition for cot theta?

OpenStudy (theislander):

answer choices

OpenStudy (anonymous):

Technically \[ \cot (\theta) = \tan(\pi/2-\theta) \]Or in general: \[ \text{co}\color{red}{\text{fun}}(\theta) = \color{red}{\text{fun}}(\pi/2-\theta) \]

OpenStudy (anonymous):

Since \[ \tan(\theta) = \frac{\sin(\theta)}{\text{cosin}(\theta)} \]We could say \[ \text{cotan}(\theta) = \frac{\text{cosin}(\theta)}{\text{cocosin}(\theta)} \]Two \(\text{co}\)s cancel out since \(\pi/2-(\pi/2-x) = x\)

OpenStudy (anonymous):

So \[ \cot(\theta) = \frac{\cos(\theta)}{\sin(\theta)} \]

OpenStudy (theislander):

thank you so much! I understand

OpenStudy (anonymous):

i always thought cot(x) = 1/tan(x) but that turned out to be false because 1/tan(x) isn't the same as cos(x)/tan(x)

OpenStudy (anonymous):

typo *cos(x)/sin(x)*

OpenStudy (anonymous):

Uhhh. \(\cot\theta = 1/\tan\theta\)

OpenStudy (anonymous):

But \[ [\tan\theta]^{-1}\neq \tan^{-1}\theta \]

OpenStudy (anonymous):

I think there is a struggle between the two definition of cot(x) and tan(x). cot(x) = cos(x)/sin(x), with sin(x) ≠ 0 tan(x) = sin(x)/cos(x), with cos(x) ≠ 0 but 1/tan(x) = 1/( sin(x)/cos(x)) with both sin(x),cos(x) ≠ 0. Now I don't what the convention is. If I graph 1/tan(x) in my calculator, then it's undefined at x = pi/2. But wolfram somehow just make cot(x) = 1/tan(x)

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