What is the value of $cot (- 315^{\circ})$ $cot(-315^@)$ ?

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Answer 1 · 2016-07-03T16:19:35

$cot (- 315^{o}) = 1$ $cot(-315^o)=1$

As $cot (- A) = - cot A$ $cot(-A)=-cotA$

$cot (- 315^{o}) = - {cot 315}^{o} = - cot (360^{o} - 45^{o})$ $cot(-315^o)=-cot315^o=-cot(360^o-45^o)$

= $- cot (- 45^{o}) = - (- {cot 45}^{o}) = {cot 45}^{o}$ $-cot(-45^o)=-(-cot45^o)=cot45^o$

But ${cot 45}^{o} = 1$ $cot45^o=1$

Hence $cot (- 315^{o}) = 1$ $cot(-315^o)=1$

What is the value of cot(−315∘)cot(-315^@)?