Coordinate Geometry
What is the shortest distance between the following 2 lines: x + y = 3 and 2x + 2y = 8?
(A) 0
(B) 1/4
(C) 1/2
(D) 2√222
(E) 2√4
Hi Anusha,
Kindly retype answer choices, above is not clear.
There are two ways solving this,
1. Use the formula
2. Plotting the points
Note: These are two lines are parallel,
x+y = 3 –> y = -x+3 –> So, slope is -1
2x+2y = 8 –> y = -x+ 4 –> So, slope again is -1. So they are parallel
After this just find the x and y intercepts of the lines and plot it.
x+y=3
(3,0) and (0,3)
x+y = 4
(4,0) and (0,4)
If we plot these you will find two isosceles triangles,
Drop a perpendicular as shown above, to find the shortest distance,
In the diagram shown above, the triangle MXN is isosceles right triangle,
So sides should be in the ratio of 1:1: sqrt(2)(angles: 45-45-90)
So, here distance has to be length opposite to the side 45 degrees .
so the shortest distance has to be, 1/sqrt(2) or we can write it as sqrt (2)/2
OR
Use the formula, shortest distance between two parallel lines = |b-c|/(sqrt(m^2 +1))
b and c intercepts and m is the slope.
you just need to substitute the values and get an answer.
Hope this helps.