The class X students school in krishnagar have been allotted a rectangular plot of land for their gardening activity. Saplings of Gulmohar are planted on the boundary at a distance of 1 m from each other. There is triangular grassy lawn in the plot as shown in the figure. The students are to sow seeds of flowering plants on the remaining area of the plot. i)Taking A as origin, find the coordinates of P. ii) What will be the coordinates of R, if C is the origin? iii) What will be the coordinates of Q, if C is the origin? iv) Find the perimeter of triangle PQR.​

Answer :

Answer:

(a) If A is the origin, then the cordinates are: P = (4, 6), Q = (3, 2), R (6, 5) respectively.

(b) The coordinates of vertices of the triangle PQR, if C is the origin: P = (-12, -2), Q = (-13, -6), R = (-10, -3)

(c) Area of triangle PQR in case of origin A:

=

1

2

[

x

1

(

y

2

y

3

)

+

x

2

(

y

3

y

1

)

+

x

3

(

y

1

y

2

)

]

=

1

2

[

4

(

2

5

)

+

3

(

5

6

)

+

6

(

6

2

)

]

=

1

2

(

12

3

+

24

)

=

9

2

s

q

u

n

i

t

Area of triangle PQR in case of origin C:

=

1

2

[

x

1

(

y

2

y

3

)

+

x

2

(

y

3

y

1

)

+

x

3

(

y

1

y

2

)

]

=

1

2

[

12

(

6

+

3

)

+

13

(

3

+

2

)

+

(

10

)

(

2

+

6

)

]

=

1

2

(

36

+

13

40

)

=

9

2

s

q

u

n

i

t

Area is same in both the cases because triangle remains the same no matter which point is considered as origin.

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