posted by Vincent on .
A plane leaves point A and flies S80° E to point B400 km away. How far east of A is B (to the nearest kilometer)?
Draw this on a graph. Put point A on the positive y-axis. From A, draw a line that looks to represent 80 degrees, to the x-axis at point B.
The distance from the origin to B is what you want to find.
In that right triangle with right angle at the origin, sin 80 degrees = x/400. Solve for x.