Test Index

NCERT Class XI Mathematics - Straight Lines - Solutions

© examsnet.com
Question : 3 of 74
Marks: +1, -0
Find the distance between P (x1,y1)(x_1, y_1) and Q (x1,y1)(x_1, y_1) when :
(i) PQ is parallel tothe y-axis,
(ii) PQ is parallel to the x-axis.
Solution:  
We are given that co-ordinates of P is (x1,y1)(x_1, y_1) and Q is (x1,y1)(x_1, y_1).Distance between the points P (x1,y1)(x_1, y_1) and Q (x1,y1)(x_1, y_1) is
PQ = (x2−x1)+(y2−y1)2\sqrt{(x_2-x_1)+(y_2-y_1)^2} ... (i)
(i) When PQ is parallel to y-axis then x1x_1 = x2x_2 from (1), we have
PQ = (x2−x1)2+(y2−y1)2\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}
= (x1−x2)2+(y2−y1)2\sqrt{(x_1-x_2)^2+(y_2-y_1)^2} = ∣y2−y1∣|y_2-y_1|
(ii) When PQ is parallel to x-axis, then y1y_1 = y2y_2 from (1), we have
PQ = (x2−x1)2+(y2−y1)2\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}
= (x2−x1)2+0\sqrt{(x_2-x_1)^2+0} = ∣x2−x1∣|x_2-x_1|
© examsnet.com
Go to Question:
Prev Question
Next Question