Question

Find the value of the trigonometric functions of cot $\left(\frac{-15\pi }{4}\right)$.

Answer 1

cot $\left(\frac{-15\pi }{4}\right)=cot\left(\frac{-15\times {180}^0}{4}\right)$

= cot $(-{675}^0)$

cot $(-{675}^0)=cot(-2\times {360}^0+{45}^0)$

= cot ${45}^0=1$