Answer:
Part A:
The surface area of a cylinder is given by
A= 6πr² if h= 2r
Part B:
Total Cost of covering the cylinder = Rate *2πrh + rate*2πr²
Cost of covering only the side = Rate *2πrh
Step-by-step explanation:
Part A:
The surface area of a cylinder is given by
A= 2πrh + 2πr²
Where h= height and radius = r
But we have the height twice as radius so h= 2r
So putting h= 2r we get
A= 2πr(2r) + 2πr²
A= 4πr² + 2πr²= 2πr²(2+1) = 2πr²(3)= 6πr²
Part B:
Cost = Rate * area of the wall + rate * area of the top and bottom
Cost = Rate *2πrh + rate*2πr²
Where area of the top and bottom= πr² +πr² =2 πr²
and area of the side = 2πrh
Multiplying both with the rate and then adding would give the total cost of materials needed to cover the outside of the cylinder and from top and bottom as well.
If you do not need to cover top and bottom then the expression would be
Cost of covering only the side = Rate *2πrh
Part C:
Already done above.
Answer:
The answer would be 0.00000007
Using the determinant method, the cross product is
so the answer is B.
Or you can apply the properties of the cross product. By distributivity, we have
(3i + 8j - 6k) x (-4i - 2j - 3k)
= -12(i x i) - 32(j x i) + 24(k x i) - 6(i x j) - 16(j x j) + 12(k x j) - 9(i x k) - 24(j x k) + 18(k x k)
Now recall that
- (i x i) = (j x j) = (k x k) = 0 (the zero vector)
- (i x j) = k
- (j x k) = i
- (k x i) = j
- (a x b) = -(b x a) for any two vectors a and b
Putting these rules together, we get
(3i + 8j - 6k) x (-4i - 2j - 3k)
= -32(-k) + 24j - 6k + 12(-i) - 9(-j) - 24i
= (-12 - 24)i + (24 + 9)j + (32 - 6)k
= -36i + 33j + 26k
