Aircraft approaching landing, vector, velocity, position problem. Help

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raven2783
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Homework Statement



As an aircraft approaches landing, the components of its position are given by:

x=81t y=500-27t

Velocity vector of aircraft during descent is given by:

81m/s (i hat) + -27m/s (j hat)

The value of the speed during the descent is:

85.381m/s

What angle does the velocity vector make with the horizonal?

2. The attempt at a solution

I tried the Law of Sines sin90/85.381=sina/-27 and sin90/85.381=sina/81 but the angles of this triangle other then 90 are not what they are looking for. What do they mean horizontal?? help!
 
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The horizontal would be your x-axis; in this case, the runway. Draw the velocity component vectors on an xy-axis. Now draw your resultant vector (the hypotenuse), which you are trying to determine the angle of. What trigonometric relation will give you this angle?

See link for formulas:

http://en.wikipedia.org/wiki/Trigonometry#Overview