# Thread: Not sure what to do with this problem (First post, by the way, Hi :)).

1. ## Not sure what to do with this problem (First post, by the way, Hi :)).

Two airplanes leave an airport at the same time. The first flies at 200 km/h in a direction of 320 degrees from due north. The second flies at 150 km/h in a direction of -87 degrees from the positive x=axis. How far apart are the planes after 1 hr, 2 hr and 3 hr? If you join the airplanes' positions by a line segment, find the area they swept between them after 1 hr, 2 hr and 3 hr.

2. ## Re: Not sure what to do with this problem (First post, by the way, Hi :)).

The only "complication" here is that the directions are given in two different forms. "320 degrees from due north" I assume is measured clockwise (as on a compass) and so the angle between the two directions is 320- (90+ 87)= 143 degrees. After one hour, the first airplane will have flown 200 km and the second 150. So you have a triangle with two sides of length 200 km and 150 km and angle between them 143 degrees. You can use the 'cosine law" to find the third side of the triangle, the straight line distance between the two airplanes.

Thanks!