Question

Which of the following is not defined?

• A. $\mathrm{Sin}90°$
• B. $\mathrm{Cos}90°$
• C. $\mathrm{Tan}90°$
• D. $\mathrm{Sin}0°$

Answer 1

The correct option is C

$\mathrm{Tan}90°$

Explanation for the correct option:

Option C.

$$\begin{gathered} \tan 90°=\frac{\sin 90°}{\cos 90°} \\ \Rightarrow \tan 90°=\frac{1}{0} \\ \therefore \tan 90°=\infty \end{gathered}$$

It is not defined.

And Hence, option $\mathrm{C}$ is the correct option.

Step 2. Explanation for the incorrect options.

Option A.

Since,$\sin 90°=1$which is defined. hence,

Therefore,option A. is the incorrect option.

Option B.

since,$\sin 0°=0$which is defined. hence,

Therefore,option B. is incorrect option.

Option D.

since,$\cos 90°=0$ which is defined. hence,

Therefore, option D. is the incorrect option.

Hence, option $\mathrm{C}$ is correct.