A straight line cuts off the intercepts OA= a and OB= b on the positive directions of x-axis and y- axis respectively. If the perpendicular from…
JEE Main 2023 — Mathematics Coordinate Geometry
2023mcqeasy
A straight line cuts off the intercepts OA=a and OB=b on the positive directions of x-axis and y− axis respectively. If the perpendicular from origin O to this line makes an angle of 6π with positive direction of y-axis and the area of △OAB is 3983, then a2−b2 is equal to:
Official previous-year question
Held on 30 Jan 2023 · Verified 6 Jul 2026.
Options
A
3392
B
196
C
3196
D
98
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Solution
Plotting the diagram of the given data we get,
Equation of straight line
Here given OA=a&OB=b, so equation of line AB in intercept form will be ax+by=1......(1)
And given perpendicular line of length p is making 3π angle with the x−axis,
So, the equation of line in normal form will be
xcos(3π)+ysin(3π)=p
⇒2px+2py3=1
So, on comparing with the equation (1) we get,
a=2p&b=\frac{2p}{\sqrt{3}}
Now area of the triangle OAB is
21×a×b=3983
⇒21×2p×32p=3983
⇒p2=49
Therefore,
a2−b2=4p2−34p2=38p2
⇒a2−b2=38(49)=3392
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