1 . cosθ=12x+1x

• A. $-\frac{1}{2}\left(x+\frac{1}{x^2}\right)$
• B. $\frac{1}{2}\left(x-\frac{1}{x^2}\right)$
• C. $\frac{1}{2}\left(x^2+\frac{1}{x^2}\right)$
• D. $\frac{1}{2}\left(\frac{1}{x^2}-x\right)$

Answer: Option D

Explanation:

2 . cosθ=1213

• A. $\frac{5}{12}$
• B. $\frac{25}{144}$
• C. $\frac{13}{12}$
• D. $\pm \frac{13}{12}$

Answer: Option A

Explanation:

3 . cosθ=12

• A. $\frac{\sqrt{3}}{2}$
• B. 1/2
• C. $\frac{1}{\sqrt{2}}$
• D. 1

Answer: Option A

Explanation: