I have given the calculations in the diagram for the values you mentioned.I was wrong abt the time interval.Its only in milliseconds not microseconds.

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If I could determine the time interval as t1~t2 =0.7 ms ,t1~t3 =0.7 ms ,I could bring out the distance and angle as follows .

velocity = distance/time.here velocty of sound is 340m/s .

d1 = v .t1=340 .t1

d2=v.(t1+(t1~t2))=340.(t1+0,7ms)

d3=v.(t1+(t1~t3)) =340.(t1+0.7 ms)

consider the rx1 to be the origin in a 2dimmensional coordinate system .this leaves us with (x1,y1) =(0 ,0) ,(x2,y2)=(0.33,0) ,(x3,y3) =(0,0.33) .(x4,y4 ) the coordinates of tx which is unknown .so by using the distance formula for d1,d2 and d3 in the above equations . x4 and y4 can be determined .from which the angle can be calculated .

Is there any error in this method ?