Answer
$\sin 90^{\circ}=1$
$\cos 90^{\circ}=0$
$\tan 90^{\circ}=\infty$ (undefined)
$\csc 90^{\circ}= 1$
$\sec 90^{\circ}=\infty$ (undefined)
$\cot 90^{\circ}=0$
Work Step by Step
When $\dfrac{\pi}{2}=\dfrac{\pi}{2} \times \dfrac{180}{\pi}=90^{\circ}$
The Trigonometric Identities can be defined as:
$\sin 90^{\circ}=1$
$\cos 90^{\circ}=0$
$\tan 90^{\circ}=\infty$ (undefined)
$\csc 90^{\circ}= 1$
$\sec 90^{\circ}=\infty$ (undefined)
$\cot 90^{\circ}=0$
