Answer:
Therefore the mass of the of the oil is 409.59 kg.
Step-by-step explanation:
Let us consider a circular disk. The inner radius of the disk be r and the outer diameter of the disk be (r+Δr).
The area of the disk
=The area of the outer circle - The area of the inner circle
= 
![=\pi [r^2+2r\triangle r+(\triangle r)^2-r^2]](https://tex.z-dn.net/?f=%3D%5Cpi%20%5Br%5E2%2B2r%5Ctriangle%20r%2B%28%5Ctriangle%20r%29%5E2-r%5E2%5D)
![=\pi [2r\triangle r+(\triangle r)^2]](https://tex.z-dn.net/?f=%3D%5Cpi%20%5B2r%5Ctriangle%20r%2B%28%5Ctriangle%20r%29%5E2%5D)
Since (Δr)² is very small, So it is ignorable.
∴
The density 
We know,
Mass= Area× density

Total mass 
Therefore

![=40\pi[ln(1+r^2)]_0^5](https://tex.z-dn.net/?f=%3D40%5Cpi%5Bln%281%2Br%5E2%29%5D_0%5E5)
![=40\pi [ln(1+5^2)-ln(1+0^2)]](https://tex.z-dn.net/?f=%3D40%5Cpi%20%5Bln%281%2B5%5E2%29-ln%281%2B0%5E2%29%5D)

= 409.59 kg (approx)
Therefore the mass of the of the oil is 409.59 kg.
Given:
A triangle has side lengths of (7.8v+2.6) centimeters, (5.3v+4.5) centimeters, and (2.4w-6.7) centimeters.
To find:
The expression which represents the perimeter, in centimeters, of the triangle.
Solution:
We know that
Perimeter of a triangle = Sum of length of all sides of the triangle

Now, combine like terms.


Therefore, the expression for perimeter, in centimeters, of the triangle is
.
It's a trick question. 1/2 is more than 2/8/