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Question -

The slope of a line is double of the slope of another line. If tangent of the angle between them is 1/3, find the slopes of the lines.



Answer -

Let us consider тАШm1тАЩ┬аandтАШmтАЩ be the slope of the two given lines such that m1┬а= 2m

We know that if ╬╕ is the angle between the lines l1 and l2 withslope m1┬аand m2, then

1+2m2┬а= -3m

2m2┬а+1 +3m = 0

2m (m+1) + 1(m+1) = 0

(2m+1) (m+1)= 0

m = -1 or -1/2

If m = -1, then the slope of the lines are -1 and -2

If m =┬а-1/2, then the slope of the linesare┬а-1/2┬аand -1

Case 2:

2m2┬атАУ 3m + 1 = 0

2m2┬атАУ 2m тАУ m + 1= 0

2m (m тАУ 1) тАУ 1(m тАУ 1) = 0

m = 1 or┬а1/2

If m = 1, then the slope of the lines are 1 and 2

If m =┬а1/2, then the slope of the linesare┬а1/2┬аand 1

тИ┤ Theslope of the lines are [-1 and -2] or┬а[-1/2┬аand -1] or [1 and 2]or┬а[1/2┬аand 1]

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