Question 71

Point Q(b,-1) is the midpoint of segment EF. Co-ordinates of point E are (-4,a) and point F are (2,0). What is the value of a and b?

Solution

Coordinates of mid point of line joining A $$(x_1,y_1)$$ and B $$(x_2,y_2)$$ = $$(\frac{x_1 + x_2}{2} , \frac{y_1 + y_2}{2})$$

Coordinates of E $$(-4 , a)$$ and F $$(2 , 0)$$

Q $$(b , -1)$$ is the mid point of EF

=> $$b = \frac{-4 + 2}{2}$$

=> $$b = \frac{-2}{2} = -1$$

Similarly, $$-1 = \frac{a + 0}{2}$$

=> $$a = -1 \times 2 = -2$$

=> Ans - (B)

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