Q. 34.0( 2 Votes )
A straight line drawn through the point A (2, 1) making an angle 
with positive x–axis intersects another line x + 2y + 1 = 0 in the point B. Find length AB.
Answer :
Given: (x1,y1) = A(2, 1), θ = 
45°
To find:
Length AB.
Explanation:
So, the equation of the line is
Formula Used: 
⇒ 
⇒ 
⇒ x – y – 1 = 0
Let PQ = r
Then, the coordinate of Q is given by
⇒ x 
, y 
The coordinate of point Q is 
Clearly, Q lies on the line x + 2y + 1 = 0
⇒ 
⇒ r 
Hence, the length of AB is 
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