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a red blood cell travels at a speed of 40 cm/s in a large artery. a sound with a frequency of 100 kHz enters a blood opposite the direction flow. calculate the frequency of sound reflected from the cell and detected by a receiver. (v = 1500 m/s)

two points A and B 80 ft apart lie on the same side of a tower and in a horizontal line through its foot . If the angle of elevation of the top of the tower at A is 21 degrees and B is 46 degrees , find the height of the tower.