1. CHAPTE R 9 9.1 9.2 The concept of Two-Dimensional Loci
Math Form 2
9.1
The concept of Two-Dimensional Loci
Intersection of Two Loci
9.2 * *

2. Locus Of A Moving Object
Locus of a point in two-dimensions is the path produced when the point moves under certain condition(s).
Locus of a point X when a girl jogs along the park is a straight horizontal line.
Locus of X * *

3. Locus Of A Moving Object
Locus of a point in two-dimensions is the path produced when the point moves under certain condition(s).
Locus of a point Y on an apple when an apple drops from a tree is a straight vertical line.
Locus of Y * *

4. Locus Of A Moving Object
Locus of a point in two-dimensions is the path produced when the point moves under certain condition(s).
Locus of a point P on the needle of a clock is a circle.
Locus of P * *

5. Locus Of A Moving Object
Locus of a point in two-dimensions is the path produced when the point moves under certain condition(s).
Locus of a point Q on a ball when the ball is thrown is a curve.
Locus of Q * *

6. Locus Of A Moving Object
Locus of a point in two-dimensions is the path produced when the point moves under certain condition(s).
Locus of a point B on a man when he runs around the football field is a rectangle.
Locus of B * *

7. Locus Of A Moving Object
Locus of a point in two-dimensions is the path produced when the point moves under certain condition(s).
Locus of a point R on the wheel of a car when it moves is a circle.
Locus of R * *

8. Locus of points (circle)
9.1b
The Locus of Points 1
The locus of points that are at a constant distance from a fixed point is a circle with radius equals to constant distance.
Locus of points (circle)
point
Fixed point
Construct a circle with radius equals to the constant distance
Constant distance (radius) * *

9. Locus of points (perpendicular bisector)2
The Locus of Points
The locus of points that are equidistant from two fixed point is the perpendicular bisector of the line joining the two fixed points.
Line P
Locus of points (perpendicular bisector)
point
Construct a perpendicular bisector of the line that joins the two fixed points.   A B l l
Fixed point
Fixed point
Line P is the perpendicular bisector of AB * *

10. The Locus of Points 3 Locus of points (parallel lines)
The locus of points that are at a constant distance from a straight line in a pair of parallel lines at the constant distance from the given straight line.
Construct parallel lines at the constant distance from the given straight line.
Locus of points (parallel lines)
Constant distance
Given straight line
Constant distance
Locus of points (parallel lines) * *

11. Locus of points (angle bisector)4
The Locus of Points
The locus of points that are equidistant from two intersecting lines is the angle bisector of the angle formed by the two intersecting lines.
Construct bisectors of the angles formed by the intersecting lines.
Locus of points (angle bisector) xº xº
2 intersecting lines * *

12. Intersecting of Two Loci
9.2
Intersecting of Two Loci
Intersecting of two loci in two dimensions is the point(s) which satisfy the conditions of the two loci. A B
For example:
CA is the locus of a moving point which is equidistant from CD and CB.
DB is the locus of a moving point which is equidistant from DA and DC o D C
O is the intersecting of the two loci. * *

13. It has finished already, good job!
1. Draw a line PQ in 3cm length.
Construct locus X of a moving point which is 2 cm from the point Q.
Construct locus Y of a moving point which is equidistant from the points P and Q.
Mark M as the point(s) of intersection of the two loci.
It has finished already, good job!
Locus X M
2 cm ll ll Q P
3 cm
M= intersection of the two loci M
Locus Y * *

14. X = intersection of the two loci
2. Draw a square ABCD with sides 3 cm. Construct:
P is the locus of a point moving in the square so that the point is 2 cm from B.
Q is the locus of a point moving in the square so that the point is equidistant from AD and DC.
Mark X as the point(s) of intersection of the two loci.
Locus Q A
3 cm D
Locus P x
3cm
Solution: Locus P is a quarter circle radius 2 cm with centre at B. Locus Q is the angle bisector of ADC, i.e, the line BD.
2 cm C B
X = intersection of the two loci * *

15. X = intersection of the two loci
3. In the diagram, ABCD is a rectangle with sides 4 cm and 3 cm. Construct:
P is the locus of a point moving in the rectangle so that it is 2 cm from AB.
Q is the locus of a point moving in the rectangle so that it is equidistant from C and D.
Mark X as the point of intersection of the two loci. A
4 cm B
Locus Q
2 cm
Locus P
3 cm x
Solution: Locus P is a parallel line, 2 cm from AB. Locus Q is the perpendicular bisector of DC. C D
X = intersection of the two loci * *

16. X = intersection of the two loci
4. Given that PQR is a triangle with sides 3 cm. Construct:
M is the locus of a point moving in the triangle so that the point is 2 cm from Q.
N is the locus of a point moving in the triangle so that it is equidistant from PR and QR.
Mark X as the point of intersection of the two loci. R
Locus N
Locus M x
2 cm
Solution: Locus M is an arc of radius 2 cm with center at Q. Locus N is the angle bisector of PRQ. P Q
X = intersection of the two loci * *

17. * *