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Posted by on Wednesday, March 23, 2011 at 11:51pm.

A boat in calm seas travels 19 km east and 32 km south. Find the distance and direction of the trip, relative to the south. What is the distance? What is the direction?

I'm confused about how to solve this problem. Could someone show me the steps?

  • Math - , Thursday, March 24, 2011 at 1:12am

    to get the resultant or the total distance, we use distance formula:
    d = sqrt[ (x2-x1)^2 + (y2-y1)^2 ]
    (x1,y1) is our reference/starting point, and
    (x2,y2) is the final point
    assuming our reference point is at the origin which is at (0,0)
    d = sqrt[ (x2)^2 + (y2)^2 ]
    d = sqrt[ (19)^2 + (-32)^2 ]
    d = 37.22 km

    *note: we use -32 since it is travelling south/downward direction

    getting the direction: let theta = angle from x-axis measured counterclockwise,,
    tan (theta) = y/x
    tan (theta) = (-32)/19
    theta = -59.3 degrees

    *note: the negative sign means opposite direction, or it is rotated clockwise

    since we need the angle to be relative to south/y-axis,
    90 - 59.3 = 30.7 degrees from south

    thus distance = 37.22 km , 30.7 degrees from south

    hope this helps~ :)

  • Math - , Thursday, March 24, 2011 at 2:36am

    Thank you so much! This definitely helped! =)

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