Physics
posted by Katsu .
A jetliner is moving at a speed of 270 m/s. The vertical component of the plane's velocity is 39.8 m/s. Determine the magnitude of the horizontal component of the plane's velocity.

This is a Pythagorean theorem problem!
x^2+y^2=c^2
i.e. (horizontal component)^2 + (vertical component)^2 = (net component)^2
plug in the values that you know and solve for the horizontal component!