Q13 of 55 Page 1

Find the value of y for which the distance between the points A(3,-1) and B(11,y) is 10 units.


 


Given: Distance between A and B = 10 units.


 


If A(x1, y1) and B(x2, y2) be two points, then the distance between points is given by:


 


(AB)2 = (x2 - x1)2 + (y2 - y1)2


 


(10)2 = (11 - 3)2 + (y – (-1))2


 


100 = (8)2 + (y + 1)2


 


100 = 64 + (y + 1)2


 


36 = (y + 1)2


 


Taking square root on both sides


 


(y + 1) = ± 6


 


y = ± 6 -1


 


Therefore y = 6 – 1 or y = - 6 -1


 


⇒ y = 5 or y = - 7


 

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