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

Jul 3, 2016

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

#### Explanation:

As $\cot \left(- A\right) = - \cot A$

$\cot \left(- {315}^{o}\right) = - \cot {315}^{o} = - \cot \left({360}^{o} - {45}^{o}\right)$

= $- \cot \left(- {45}^{o}\right) = - \left(- \cot {45}^{o}\right) = \cot {45}^{o}$

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

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