Question

Two lines $$2x-3y=1$$   and $$x+2y+3=0$$    divide the $$x$$-$$y$$ plane in four compartments which are named as shown in the figure. Consider the locations of the points $$\left( {2,\, - 1} \right)\left( {3,\,2} \right)$$   and $$\left( { - 1,\, - 2} \right).$$  We get
Straight Lines mcq question image

A. $$\left( {2,\, - 1} \right) \in \,{\text{IV}}$$  
B. $$\left( {3,\,2} \right)\, \in \,{\text{III}}$$
C. $$\left( { - 1,\, - 2} \right)\, \in \,{\text{II}}$$
D. none of these
Answer :   $$\left( {2,\, - 1} \right) \in \,{\text{IV}}$$
Solution :
Consider the first line
$$\eqalign{ & 2x - 3y = 1 \cr & \frac{x}{{\frac{1}{2}}} - \frac{y}{{\frac{1}{3}}} = 1 \cr} $$
Hence the intercepts are $$\frac{1}{2}$$ and $$\left( { - \frac{1}{3}} \right)......\left( {\text{i}} \right)$$
Similarly for the second line $$\frac{x}{{ - 3}} + \frac{y}{{\frac{{ - 3}}{2}}} = 1$$
Hence it has intercepts $$-3$$  and $$-1.5$$
Now both the lines intersect at $$\left( { - 1,\, - 1} \right)$$
This will be our origin.
Hence
Now consider the point $$\left( {2,\, - 1} \right)$$
Substituting the point in $$2x - 3y - 1 = 0$$
We get
$$8 > 0......\left( {\text{i}} \right)$$
Substituting it in $$x + 2y + 3 = 0$$
$$3 > 0......\left( {{\text{ii}}} \right)$$
Clearly from i and ii, it will lie in the new iv quadrant. Similarly applying the above steps for the point $$\left( {3,\,2} \right)$$  and $$\left( { - 1,\,2} \right)$$  we get that the point $$\left( {3,\,2} \right)$$  lies in the new first quadrant while the point $$\left( { - 1,\, - 2} \right)$$  lies in the new IIIrd quadrant.

Releted MCQ Question on
Geometry >> Straight Lines

Releted Question 1

The points $$\left( { - a, - b} \right),\left( {0,\,0} \right),\left( {a,\,b} \right)$$     and $$\left( {{a^2},\,ab} \right)$$  are :

A. Collinear
B. Vertices of a parallelogram
C. Vertices of a rectangle
D. None of these
Releted Question 2

The point (4, 1) undergoes the following three transformations successively.
(i) Reflection about the line $$y =x.$$
(ii) Translation through a distance 2 units along the positive direction of $$x$$-axis.
(iii) Rotation through an angle $$\frac{p}{4}$$ about the origin in the counter clockwise direction.
Then the final position of the point is given by the coordinates.

A. $$\left( {\frac{1}{{\sqrt 2 }},\,\frac{7}{{\sqrt 2 }}} \right)$$
B. $$\left( { - \sqrt 2 ,\,7\sqrt 2 } \right)$$
C. $$\left( { - \frac{1}{{\sqrt 2 }},\,\frac{7}{{\sqrt 2 }}} \right)$$
D. $$\left( {\sqrt 2 ,\,7\sqrt 2 } \right)$$
Releted Question 3

The straight lines $$x + y= 0, \,3x + y-4=0,\,x+ 3y-4=0$$         form a triangle which is-

A. isosceles
B. equilateral
C. right angled
D. none of these
Releted Question 4

If $$P = \left( {1,\,0} \right),\,Q = \left( { - 1,\,0} \right)$$     and $$R = \left( {2,\,0} \right)$$  are three given points, then locus of the point $$S$$ satisfying the relation $$S{Q^2} + S{R^2} = 2S{P^2},$$    is-

A. a straight line parallel to $$x$$-axis
B. a circle passing through the origin
C. a circle with the centre at the origin
D. a straight line parallel to $$y$$-axis

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Straight Lines


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