Question

Which expression equals -1?

Answer 1

Answer:

Option D. is correct.

Step-by-step explanation:

$\cot ^{\left(2\right)}\left(73^{\circ \:}\right)-\csc ^{\left(2\right)}\left(73^{\circ \:}\right)$

$\csc \left(73^{\circ \:}\right)=\frac{1}{\sin \left(73^{\circ \:}\right)}$

$=\cot ^2\left(73^{\circ \:}\right)-\left(\frac{1}{\sin \left(73^{\circ \:}\right)}\right)^2$

$\left(\frac{1}{\sin \left(73^{\circ \:}\right)}\right)^2 = \left\frac{1}{\sin^2 \left(73^{\circ \:}\right)}\right$

$=\cot ^2\left(73^{\circ \:}\right)-\frac{1}{\sin ^2\left(73^{\circ \:}\right)}$

Which is the same as...

$-1$