Answer:
2.12
Explanation:
Discussion
The answer is given in the graph I've made for you. The distance you want is a contained in a line that is perpendicular to the given line and goes through (2,-1). If I have not interpreted this correctly please leave a comment under the question and I will edit it. I have ignored the 4.
The steps needed are
- Find the slope of the line perpendicular to y = - x + 4
- Find the intersection point on y = - x + 4 and the new line.
- Use the distance formula to find the distance from (2,-1) to the intersection point found in the second step
Givens
line y = -x + 4
point (2,-1)
Solution
The slope of the second line is
m1 * m2 = - 1
m1= -1 From the given equation
m2 = ?
-1 * m2 = - 1
m2 = 1
Find the equation of the new line
x = 2
y = - 1 from the given point
-1 = 2 + b Subtract 2 from both sides
-1 - 2 = 2-2 + b Combine
-3 = b
Equation of the new line
y = x - 3
Intersection point of the two lines
y = -x + 4
y = x - 3 Add The xs cancel
2y = 1 Divide by 2
y = 1/2
1/2 = -x + 4 Subtract 4 from both sides
1/2 - 4 = -x + 4 -4 Combine
-3 1/2 = -x Multiply both sides by - 1
3 1/2 = x
So the intersection point is (3.5, 0.5)
Find the distance between (2,-1) and (3.5,0.5)
d = sqrt( (2 - 3.5)^2 + (-1 - 0.5)^2 )
d = sqrt( (-1.5)^2 + (-1.5)^2 )
d = ( 1..5 * sqrt(2) )
d = 2.12