science
posted by jo1475 .
a boat heading due north crosses a wide river with speed of 12km/h relative to the water the water in the river has a uniform speed of 5 km/h due east relative to the earth.determine the velocity of the boat relative to an observer standing on either bank and the direction of boat

Do vector addition of the two velocities to obtain boat's velocity V w.r.t.river bank:
V = sqrt(12^2+5^2) = 13 Km/hr
and
tan theta = 5/12; (theta  angle between V and north)