Find the y-intercept of (0,2), (2,-1)

Express the following as a function of a single angle. cos(60) cos(-20) - sin(60) sin(-20)

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.

If you could answer these your a life saver