The diameter of a circle is 18 miles. What is the circle's area?
Use 3.14 for .

254.34

Step-by-step explanation:

The area of a circle = pi * r^2 where pi = 3.14 and r = radius of the circle, which is the length of any line drawn from the center of the circle to the circle’s edge.

The diameter of a circle is the distance of a line from one point on the edge of the circle to another point on the edge of the circle, passing through the center. It’s the longest line you can draw from one edge of a circle to another edge. It is equal to 2r.

So here, 2r = 18 and r = 9. Therefore, we plug the value for r into the area equation above and get:

A = pi * r^2 = 3.14*(9^2) = 3.14*81 = 254.34

456567546657689765432567890-9876543567890-987657890

step-by-step explanation:

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