Answer:
5cm = r
Step-by-step explanation:
The area of a circle is given by
A = pi r^2
78.5 = 3.14 r^2
Divide each side by 3.14
78.5/ 3.14 = r^2
25 = r^2
Take the square root of each side
sqrt(25) = sqrt(r^2)
5 = r
Answer:
65.56°
Step-by-step explanation:
We know that if we take dot product of two vectors then it is equal to the product of magnitudes of the vectors and cosine of the angle between them
That is let p and q be any two vectors and A be the angle between them
So, p·q=|p|*|q|*cosA
⇒
Given u=-8i-3j and v=-8i+8j
let A be angle before u and v
therefore, 
⇒
Therefore angle between u and v is 65.56°
Answer:
3.5 hours
Step-by-step explanation:
if you multiply 6 and 2 by 3.5, then add them you get 28
Alrighty
squaer base so length=width, nice
v=lwh
but in this case, l=w, so replace l with w
V=w²h
and volume is 32000
32000=w²h
the amount of materials is the surface area
note that there is no top
so
SA=LW+2H(L+W)
L=W so
SA=W²+2H(2W)
SA=W²+4HW
alrighty
we gots
SA=W²+4HW and
32000=W²H
we want to minimize the square foottage
get rid of one of the variables
32000=W²H
solve for H
32000/W²=H
subsitute
SA=W²+4WH
SA=W²+4W(32000/W²)
SA=W²+128000/W
take derivitive to find the minimum
dSA/dW=2W-128000/W²
where does it equal 0?
0=2W-1280000/W²
128000/W²=2W
128000=2W³
64000=W³
40=W
so sub back
32000/W²=H
32000/(40)²=H
32000/(1600)=H
20=H
the box is 20cm height and the width and length are 40cm
X=2 I believe but I need to keep typing to make it longer
