Question

if cos theta =2/3 find 2sec^2 theta + tan^2theta-7

Answer 1

You will need to use the following pieces of information:

\[\sin^2\theta + \cos^2\theta = 1\]
\[\tan \theta = \frac{\sin \theta}{\cos \theta}\]
\[\sec \theta = \frac{1}{\cos \theta}\]

Answer 2

since all of these things are either sin or cos, and we already have cos, we should find sin first using the first formula.

Answer 3

see if you can make any progress with that idea. :)