1. Find the ratio in which the point P (3/4, 5/12) divides the line segment joining the points A(1/2, 3/2) and B(2, -5)
1. Find the ratio in which the point P(3/4,5/12) divides the line segment joining the points A(1/2,3/2) and B(2,-5)
Solution: Method-1 : considering the ratio m:n
Suppose P(3/4,5/12) divides the line joining A(1/2,3/2) and B(2,-5) in the ratio m:n
Using section formula P(x,y)=((mx_2+nx_1)/(m+n),(my_2+ny_1)/(m+n))
:.P(3/4,5/12)=((m(2)+n(1/2))/(m+n),(m(-5)+n(3/2))/(m+n))
:.(m(2)+n(1/2))/(m+n)=3/4 and (m(-5)+n(3/2))/(m+n)=5/12
Now, solving first :. (m(2)+n(1/2))/(m+n)=3/4
:. 4(2m+(n)/(2))=3(m+n)
:. 8m+2n=3m+3n
:. 8m-3m=3n-2n
:. 5m=n
:. m/n=(1)/(5)
:. The point P(3/4,5/12) divides the line joining A(1/2,3/2) and B(2,-5) in the ratio 1:5
Method-2 : considering the ratio k:1
Suppose P(3/4,5/12) divides the line joining A(1/2,3/2) and B(2,-5) in the ratio k:1
Using section formula P(x,y)=((kx_2+x_1)/(k+1),(ky_2+y_1)/(k+1))
:.P(3/4,5/12)=((k(2)+(1/2))/(k+1),(k(-5)+(3/2))/(k+1))
:.(k(2)+(1/2))/(k+1)=3/4 and (k(-5)+(3/2))/(k+1)=5/12
Now, solving first :. (k(2)+(1/2))/(k+1)=3/4
:. 4(2k+1/2)=3(k+1)
:. 8k+2=3k+3
:. 8k-3k=3-2
:. 5k=1
:. k=(1)/(5)
:. The point P(3/4,5/12) divides the line joining A(1/2,3/2) and B(2,-5) in the ratio 1:5

2. Find the ratio in which the point P(-1,6) divides the line segment joining the points A(3,10) and B(6,-8)
Solution: Method-1 : considering the ratio m:n
Suppose P(-1,6) divides the line joining A(3,10) and B(6,-8) in the ratio m:n
Using section formula P(x,y)=((mx_2+nx_1)/(m+n),(my_2+ny_1)/(m+n))
:.P(-1,6)=((m(6)+n(3))/(m+n),(m(-8)+n(10))/(m+n))
:.(m(6)+n(3))/(m+n)=-1 and (m(-8)+n(10))/(m+n)=6
Now, solving first :. (m(6)+n(3))/(m+n)=-1
:. 6m+3n=-1(m+n)
:. 6m+3n=-m-n
:. 6m+m=-n-3n
:. 7m=-4n
:. m/n=(-4)/(7)
As the ratio is negative, the point P(-1,6) divides the line joining A(3,10) and B(6,-8) externally in the ratio 4:7
Method-2 : considering the ratio k:1
Suppose P(-1,6) divides the line joining A(3,10) and B(6,-8) in the ratio k:1
Using section formula P(x,y)=((kx_2+x_1)/(k+1),(ky_2+y_1)/(k+1))
:.P(-1,6)=((k(6)+(3))/(k+1),(k(-8)+(10))/(k+1))
:.(k(6)+(3))/(k+1)=-1 and (k(-8)+(10))/(k+1)=6
Now, solving first :. (k(6)+(3))/(k+1)=-1
:. 6k+3=-1(k+1)
:. 6k+3=-k-1
:. 6k+k=-1-3
:. 7k=-4
:. k=(-4)/(7)
As the ratio is negative, the point P(-1,6) divides the line joining A(3,10) and B(6,-8) externally in the ratio 4:7

3. Find the ratio in which the point P(-2,3) divides the line segment joining the points A(-3,5) and B(4,-9)
Solution: Method-1 : considering the ratio m:n
Suppose P(-2,3) divides the line joining A(-3,5) and B(4,-9) in the ratio m:n
Using section formula P(x,y)=((mx_2+nx_1)/(m+n),(my_2+ny_1)/(m+n))
:.P(-2,3)=((m(4)+n(-3))/(m+n),(m(-9)+n(5))/(m+n))
:.(m(4)+n(-3))/(m+n)=-2 and (m(-9)+n(5))/(m+n)=3
Now, solving first :. (m(4)+n(-3))/(m+n)=-2
:. 4m-3n=-2(m+n)
:. 4m-3n=-2m-2n
:. 4m+2m=-2n+3n
:. 6m=n
:. m/n=(1)/(6)
:. The point P(-2,3) divides the line joining A(-3,5) and B(4,-9) in the ratio 1:6
Method-2 : considering the ratio k:1
Suppose P(-2,3) divides the line joining A(-3,5) and B(4,-9) in the ratio k:1
Using section formula P(x,y)=((kx_2+x_1)/(k+1),(ky_2+y_1)/(k+1))
:.P(-2,3)=((k(4)+(-3))/(k+1),(k(-9)+(5))/(k+1))
:.(k(4)+(-3))/(k+1)=-2 and (k(-9)+(5))/(k+1)=3
Now, solving first :. (k(4)+(-3))/(k+1)=-2
:. 4k-3=-2(k+1)
:. 4k-3=-2k-2
:. 4k+2k=-2+3
:. 6k=1
:. k=(1)/(6)
:. The point P(-2,3) divides the line joining A(-3,5) and B(4,-9) in the ratio 1:6

4. Find the ratio in which the point P(3,10) divides the line segment joining the points A(5,12) and B(2,9)
Solution: Method-1 : considering the ratio m:n
Suppose P(3,10) divides the line joining A(5,12) and B(2,9) in the ratio m:n
Using section formula P(x,y)=((mx_2+nx_1)/(m+n),(my_2+ny_1)/(m+n))
:.P(3,10)=((m(2)+n(5))/(m+n),(m(9)+n(12))/(m+n))
:.(m(2)+n(5))/(m+n)=3 and (m(9)+n(12))/(m+n)=10
Now, solving first :. (m(2)+n(5))/(m+n)=3
:. 2m+5n=3(m+n)
:. 2m+5n=3m+3n
:. 2m-3m=3n-5n
:. -m=-2n
:. m=2n
:. m/n=(2)/(1)
:. The point P(3,10) divides the line joining A(5,12) and B(2,9) in the ratio 2:1
Method-2 : considering the ratio k:1
Suppose P(3,10) divides the line joining A(5,12) and B(2,9) in the ratio k:1
Using section formula P(x,y)=((kx_2+x_1)/(k+1),(ky_2+y_1)/(k+1))
:.P(3,10)=((k(2)+(5))/(k+1),(k(9)+(12))/(k+1))
:.(k(2)+(5))/(k+1)=3 and (k(9)+(12))/(k+1)=10
Now, solving first :. (k(2)+(5))/(k+1)=3
:. 2k+5=3(k+1)
:. 2k+5=3k+3
:. 2k-3k=3-5
:. -k=-2
:. k=2
:. k=(2)/(1)
:. The point P(3,10) divides the line joining A(5,12) and B(2,9) in the ratio 2:1

5. Find the ratio in which the point P(6,17) divides the line segment joining the points A(1,-3) and B(3,5)
Solution: Method-1 : considering the ratio m:n
Suppose P(6,17) divides the line joining A(1,-3) and B(3,5) in the ratio m:n
Using section formula P(x,y)=((mx_2+nx_1)/(m+n),(my_2+ny_1)/(m+n))
:.P(6,17)=((m(3)+n(1))/(m+n),(m(5)+n(-3))/(m+n))
:.(m(3)+n(1))/(m+n)=6 and (m(5)+n(-3))/(m+n)=17
Now, solving first :. (m(3)+n(1))/(m+n)=6
:. 3m+n=6(m+n)
:. 3m+n=6m+6n
:. 3m-6m=6n-n
:. -3m=5n
:. 3m=-5n
:. m/n=(-5)/(3)
As the ratio is negative, the point P(6,17) divides the line joining A(1,-3) and B(3,5) externally in the ratio 5:3
Method-2 : considering the ratio k:1
Suppose P(6,17) divides the line joining A(1,-3) and B(3,5) in the ratio k:1
Using section formula P(x,y)=((kx_2+x_1)/(k+1),(ky_2+y_1)/(k+1))
:.P(6,17)=((k(3)+(1))/(k+1),(k(5)+(-3))/(k+1))
:.(k(3)+(1))/(k+1)=6 and (k(5)+(-3))/(k+1)=17
Now, solving first :. (k(3)+(1))/(k+1)=6
:. 3k+1=6(k+1)
:. 3k+1=6k+6
:. 3k-6k=6-1
:. -3k=5
:. 3k=-5
:. k=(-5)/(3)
As the ratio is negative, the point P(6,17) divides the line joining A(1,-3) and B(3,5) externally in the ratio 5:3

6. Find the ratio in which the point P(12,23) divides the line segment joining the points A(2,8) and B(6,14)
Solution: Method-1 : considering the ratio m:n
Suppose P(12,23) divides the line joining A(2,8) and B(6,14) in the ratio m:n
Using section formula P(x,y)=((mx_2+nx_1)/(m+n),(my_2+ny_1)/(m+n))
:.P(12,23)=((m(6)+n(2))/(m+n),(m(14)+n(8))/(m+n))
:.(m(6)+n(2))/(m+n)=12 and (m(14)+n(8))/(m+n)=23
Now, solving first :. (m(6)+n(2))/(m+n)=12
:. 6m+2n=12(m+n)
:. 6m+2n=12m+12n
:. 6m-12m=12n-2n
:. -6m=10n
:. 6m=-10n
:. m/n=(-10)/(6)
:. m/n=(-5)/(3)
As the ratio is negative, the point P(12,23) divides the line joining A(2,8) and B(6,14) externally in the ratio 5:3
Method-2 : considering the ratio k:1
Suppose P(12,23) divides the line joining A(2,8) and B(6,14) in the ratio k:1
Using section formula P(x,y)=((kx_2+x_1)/(k+1),(ky_2+y_1)/(k+1))
:.P(12,23)=((k(6)+(2))/(k+1),(k(14)+(8))/(k+1))
:.(k(6)+(2))/(k+1)=12 and (k(14)+(8))/(k+1)=23
Now, solving first :. (k(6)+(2))/(k+1)=12
:. 6k+2=12(k+1)
:. 6k+2=12k+12
:. 6k-12k=12-2
:. -6k=10
:. 6k=-10
:. k=(-10)/(6)
:. k=(-5)/(3)
As the ratio is negative, the point P(12,23) divides the line joining A(2,8) and B(6,14) externally in the ratio 5:3

This material is intended as a summary. Use your textbook for detail explanation. Any bug, improvement, feedback then
|