A ship heads due north for x miles, then turns 25 degrees east of north and travels for another y miles. Which expression represents the distance the ship is from the original starting point?

The ship’s two displacement vectors have lengths x and y, with an angle of 25° between them. In the triangle from the start to the endpoint, the included angle is 155° because the first leg points south when viewed from the endpoint. By the law of cosines, the distance is √(x² + y² − 2xy cos 155°), which is choice C.

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