JEE MainMathematicsStraight Lines and Pair of Straight LinesMCQ+4 / −1
Let a triangle be bounded by the lines L1 : 2x + 5y = 10; L2 : 4x + 3y = 12 and the line L3, which passes through the point P(2, 3), intersects L2 at A and L1 at B. If the point P divides the line-segment AB, internally in the ratio 1 : 3, then the area of the triangle is equal to :
- A
- B
- C
- D
View written solutionFree
Correct answer: B
- Given lines
A third line passes through , meets at and at .
Also, divides internally in the ratio .
- Use section formula
Since divides internally in the ratio , we interpret
If and , then by section formula,
So,
Since ,
Hence,
Let
Because lies on and lies on ,
and from ,
- Solve for and
From (3) and (4),
Substitute into (2):
Now solve (1) and (5):
Multiply the second by :
Add with the first:
Then from (5):
Therefore,
Now,
Hence,
- Find the third vertex of the triangle
The triangle is bounded by .
Its vertices are:
Find by solving:
Multiply first by :
Add with second:
Then
So,
- Compute area of triangle
Use determinant formula:
Take
Then
So,
Since and ,
- Check with options
So the correct option is B.
- Comparison with stored answer
Stored correct answer: B
Derived answer: B
They agree.
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