Coordinate GeometryClass 10 Mathematics NCERT Solutions

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Q1Exercise 7.1

Find the distance between the following pairs of points :

(i)

(2,3),(4,1)(2,3),(4,1)

(ii)

(−5,7),(−1,3)(-5,7),(-1,3)

(iii)

(a,b),(−a,−b)(a, b),(-a,-b)

Solution

Formula: The distance between two points P(x1,y1)P(x_1, y_1) and Q(x2,y2)Q(x_2, y_2) is given by the distance formula: d=(x2−x1)2+(y2−y1)2d = \sqrt{(x_2 - x_1)^2 + (y_2 - y_1)^2}
(i) Points (2,3)(2,3) and (4,1)(4,1)
Given: Let (x1,y1)=(2,3)(x_1, y_1) = (2, 3) and (x2,y2)=(4,1)(x_2, y_2) = (4, 1).
Solution: Distance =(4−2)2+(1−3)2= \sqrt{(4 - 2)^2 + (1 - 3)^2} =(2)2+(−2)2= \sqrt{(2)^2 + (-2)^2} =4+4= \sqrt{4 + 4} =8= \sqrt{8} =22= 2\sqrt{2}
Final Answer: The distance between the points (2,3)(2,3) and (4,1)(4,1) is 222\sqrt{2} units.

(ii) Points (−5,7)(-5,7) and (−1,3)(-1,3)
Given: Let (x1,y1)=(−5,7)(x_1, y_1) = (-5, 7) and (x2,y2)=(−1,3)(x_2, y_2) = (-1, 3).
Solution: Distance =(−1−(−5))2+(3−7)2= \sqrt{(-1 - (-5))^2 + (3 - 7)^2} =(−1+5)2+(−4)2= \sqrt{(-1 + 5)^2 + (-4)^2} =(4)2+(−4)2= \sqrt{(4)^2 + (-4)^2} =16+16= \sqrt{16 + 16} =32= \sqrt{32} =42= 4\sqrt{2}
Final Answer: The distance between the points (−5,7)(-5,7) and (−1,3)(-1,3) is 424\sqrt{2} units.

(iii) Points (a,b)(a, b) and (−a,−b)(-a, -b)
Given: Let (x1,y1)=(a,b)(x_1, y_1) = (a, b) and (x2,y2)=(−a,−b)(x_2, y_2) = (-a, -b).
Solution: Distance =(−a−a)2+(−b−b)2= \sqrt{(-a - a)^2 + (-b - b)^2} =(−2a)2+(−2b)2= \sqrt{(-2a)^2 + (-2b)^2} =4a2+4b2= \sqrt{4a^2 + 4b^2} =4(a2+b2)= \sqrt{4(a^2 + b^2)} =2a2+b2= 2\sqrt{a^2 + b^2}
Final Answer: The distance between the points (a,b)(a, b) and (−a,−b)(-a, -b) is 2a2+b22\sqrt{a^2 + b^2} units.