Answer:
\(cos(\frac{t}{2} ) = -\sqrt\frac{1}{11}\)
Step-by-step explanation:
The relationship between cos(t) and cos(\(\frac{t}{2}\)) is:
\(cos(\frac{t}{2} ) = a\sqrt\frac{1+cos(t)}{2}\)
where a is equal to +1 or -1 is same as same sign which cos(t) holds.
Thus, \(cos(\frac{t}{2} ) = -\sqrt\frac{1-\frac{9}{11}}{2}\)
⇒ \(cos(\frac{t}{2} ) = -\sqrt\frac{11-9}{2\times 11}\)
⇒ \(cos(\frac{t}{2} ) = -\sqrt\frac{2}{22}\)
⇒ \(cos(\frac{t}{2} ) = -\sqrt\frac{1}{11}\)
