Question

Period of $12\cot^{2}\theta - 31\cos ⥂ ec\theta + 32 = 0$is.

• A. $12(\text{cos} ⥂ \text{e}\text{c}^{2}\theta - 1) - 31\text{cos} ⥂ \text{ec }\theta + \text{32} = 0$
• B. $12\text{cos} ⥂ \text{e}\text{c}^{2}\theta - 31\text{cos} ⥂ \text{ec }\theta + \text{20} = 0$
• C. $12\text{cos} ⥂ \text{e}\text{c}^{2}\theta - 16\text{cos} ⥂ \text{ec }\theta - 15\text{cos} ⥂ \text{ec}\theta + 20 = 0$
• D. None of these

Answer 1

Answer: (B)

$12\text{cos} ⥂ \text{e}\text{c}^{2}\theta - 31\text{cos} ⥂ \text{ec }\theta + \text{20} = 0$

Answer 2

Since $\cos^{2}A + \cos^{2}C = \cos^{2}A + \cos^{2}\left( \frac{\pi}{2} - A \right)$. Hence period = $= \cos^{2}A + \sin^{2}A = 1$.