A map of barn is shown in coordinate plane in which the coordinates are measured in yards. The map shows the barn a (4,6). A well is dug at (4, y). What are the two values of y such that the barn is 70 yards from the well

The values of y such that the barn is 70 yards from the well are y=76 or y=-64

Step-by-step explanation:

Distance in the Plane

Given two points in a rectangular system of coordinates (a,b) and (c,d) the distance measured between them is calculated with the formula

The barn is located at (4,6) and the well is located at (4,y). The value of y must be calculated in such a way the distance between the barn and the well is 70 yards. Thus, the equation to solve is

Operating

When taking the square root we must be careful for it has two signs:

Rearranging

which yields to these solutions

And also

The values of y such that the barn is 70 yards from the well are y=76 yards or y=-64 yards

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12

good job you smart son of a gun you are smarter that einstein. 7