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NCERT Class XI Mathematics - Straight Lines - Solutions

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Question : 4 of 74
Marks: +1, -0
Find a point on the x-axis, which is equidistant from the points (7, 6) and (3, 4).
Solution:  
Let the point be P(x, y). Since it lies on the x-axis
∴ y = 0 i.e., required point be (x, 0). Since the required point is equidistant from points A(7, 6) and B(3, 4) ⇒ PA = PB
⇒ (x−7)2+(0−6)2\sqrt{(x-7)^2+(0-6)^2} = (x−3)2+(0−4)2\sqrt{(x-3)^2+(0-4)^2}
⇒ x2+49−14x+36\sqrt{x^2+49-14x+36} = x2+9−6x+16\sqrt{x^2+9-6x+16}
⇒ x2x^2 - 14x + 85 = x2x^2 - 6x + 25 ⇒ - 14x + 6x = 25 - 85 ⇒ 8x = 60
⇒ x = 152\frac{15}{2}
∴ The required point is (152,0)\left(\frac{15}{2},0\right)
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