How do you find the exact values of cot, csc and sec for 90 degrees?

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Answer 1 · 2018-04-13T17:27:37

$color(blue)(csc(90^@)=1)$

Identities:

$color(red)bb(cotx=1/tanx)$

$color(red)bb(cscx=1/sinx)$

$color(red)bb(secx=1/cosx)$

We know:

$sin(90^@)=1$

$cos(90^@)=0$

$tan(90^@)$ is undefined. This is because:

as $theta->90^@, tan(theta)->oo$

$:.$

$csc(90^@)=1/1=color(blue)(1)$

$sec(90^@)=1/0$ This is also undefined. ( division by zero )

$cot(90^@)$ This is also undefind, because $tan(90^@)$ is undefined.