Which could be the first step in solving the equation represented by the model below

In the figure below, ∠dec ≅ ∠dce, ∠b ≅ ∠f, and segment df is congruent to segment bd. point c is the point of intersection between segment ag and segment bd, while point e is the point of intersection between segment ag and segment df. the figure shows a polygon comprised of three triangles, abc, dec, and gfe. prove δabc ≅ δgfe.

Which number completes the inequality? 2/3 < _ < 7/9

If the value of cos330°is√3/2 then find cos 165°.