Write the following in terms of sine, using the cofunction relationship. cos(7pi/9)

Write your angle in radians.

That's going to depend heavily on where you're coming from.  Grand Prairie is a western suburb of Dallas.  If you live in Arlington, then it's a quick jaunt of a few miles.  But if you're starting out from, let's say, Seattle, then you're looking at a good 2,000 miles, and you have to plan on 3 or 4 days on the road.