Question Details

Two lines L1 and L2 passing through origin trisecting the line segment intercepted by the line 4x+ 5y = 20 between the coordinate axes. Then the tangent of angle between the lines L1 and L2 is

Options

A

√3

B

1/√3

C

1

D

30/41

Correct Answer :

30/41

Solution :

The correct option is 30/41.

Step-by-Step Explanation:

Step 1: Find the intercepts of the given line on the coordinate axes
The given equation of the line is:
4x+5y=20
To find the x-intercept, we set y=0:
4x=20x=5
This gives the point on the x-axis, which is labeled as P(5,0) in the provided image.
To find the y-intercept, we set x=0:
5y=20y=4
This gives the point on the y-axis, which is labeled as Q(0,4) in the provided image.
Thus, the line segment intercepted between the axes is PQ connecting P(5,0) and Q(0,4).

Step 2: Determine the trisection points of the segment PQ
As observed in the image, the two lines passing through the origin O(0,0) trisect the line segment PQ at two points, labeled as A and B.
Point A divides the segment QP in the ratio 1:2 (closer to Q). Using the section formula:
xA=15+201+2=53
yA=10+241+2=83
So, the coordinates of point A are (53,83), which matches the label in the image.
Point B divides the segment QP in the ratio 2:1 (closer to P). Using the section formula:
xB=25+102+1=103
yB=20+142+1=43
So, the coordinates of point B are (103,43), which also matches the label in the image.

Step 3: Calculate the slopes of the lines OA and OB
The line L1 is the line OA passing through (0,0) and A(53,83). Its slope m1 is:
m1=8/35/3=85
The line L2 is the line OB passing through (0,0) and B(103,43). Its slope m2 is:
m2=4/310/3=410=25

Step 4: Find the tangent of the angle between the two lines
Let θ be the angle between the lines L1 and L2. The formula for the tangent of the angle between two lines with slopes m1 and m2 is:
tanθ=|m1-m21+m1m2|
Substituting the values of m1 and m2:
tanθ=|85-251+(85)(25)|
Simplify the numerator:
85-25=65
Simplify the denominator:
1+1625=4125
Now divide the two terms:
tanθ=6/541/25=652541=3041
Thus, the tangent of the angle between the lines L1 and L2 is 3041.

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