Test Index
NCERT Class XI Mathematics - Straight Lines - Solutions
© examsnet.com
Question : 46 of 74
Marks:
+1,
-0
Two lines passing through the point (2, 3) intersects each other at an angle of 60°. If slope of one line is 2, find equation of the other line.
Solution:
We have given a point (2, 3), through which two lines are passing and intersects at an angle of 60°. Let m be the slope of the other line ⇒ tan 60° = ⇒ ± = ⇒ = ... (i) or - = ... (ii) ⇒ = m - 2 or = 2 - m ⇒ + 2 = m - m or m + m = 2 - ⇒ m = or m = Since the line passes through (2, 3) ∴ Its equation is either y - 3 = ... (iii) or y - 3 = ... (iv) (iii) ⇒ (y − 3)(1 − 2) = ( + 2) (x − 2) ⇒ y (1 − 2) − 3(1 − 2) = ( + 2)x − 2( + 2) ⇒ y (1 − 2) − (3 − 6 ) = ( + 2)x − 2 −4 ⇒ 2 + 4 − 3 + 6 =( + 2)x +(2 − 1)y ⇒( + 2)x + (2 − 1)y− 8 − 1 = 0 ... (v) And (iv) ⇒ (y − 3) (1 + 2) = (2 − ) (x −2) ⇒ y(1 + 2) − 3 (1 + 2) = (2 − )x − 2(2 − ) ⇒ − 3 − 6 + 2(2 − ) = (2 − )x− y(1+ 2 ) ⇒ − 3 − 6 +4 − 2 =(2 − )x − y (1 + 2 ) ⇒ (2 − )x −(1 + 2 )y + 8 − 1 = 0 ... (vi) Thus (v) and (vi) are the required equations of the line.
© examsnet.com
Go to Question: