trigo, grade 10, question 8

29/11/2016 Grade 10 2,641

8) Given :

4{\cos^2}x+{\sin ^2}x=3

where 

x\in\left[{\frac{\pi }{2},\pi}\right]

  1. Verify that cosx =

    \frac{{-\sqrt6}}{3}

  2. Deduce sinx.
  3. Evaluate: 

    \tan\left({7\pi+x}\right)+\sin\left({\frac{{13\pi }}{2}+x}\right)-\cos\left({\frac{{16\pi - 4x}}{4}}\right)