I love these. It's often called the Shoelace Formula. It actually works for the area of any 2D polygon.
We can derive it by first imagining our triangle in the first quadrant, one vertex at the origin, one at (a,b), one at (c,d), with (0,0),(a,b),(c,d) in counterclockwise order.
Our triangle is inscribed in the 
rectangle. There are three right triangles in that rectangle that aren't part of our triangle. When we subtract the area of the right triangles from the area of the rectangle we're left with the area S of our triangle.
That's the cross product in the purest form. When we're away from the origin, a arbitrary triangle with vertices 
will have the same area as one whose vertex C is translated to the origin.
We set 
That's a perfectly useful formula right there. But it's usually multiplied out:
That's the usual form, the sum of cross products. Let's line up our numbers to make it easier.
(1, 2), (3, 4), (−7, 7)
(−7, 7),(1, 2), (3, 4),
[tex]A = \frac 1 2 ( 1(7)-2(-7) + 3(2)-4(1) + -7(4) - (7)(3)
So for the first one, you would have to multiply 2 six times. and then 2 with a -4 exponent is a little challenging. Okay, you would have to make it a fraction. so it would be 1/16. then you would just multiply 2 seven times.
Answer:
Option (C) and (D)
Step-by-step explanation:
Given piecewise function is,
f(x) = 2x, x < 1
5, x = 1
, x > 1
Option (A),
x = 5 means x > 1
So the function will be,
f(x) =
f(5) = (5)²
= 25
Therefore, f(5) = 1 is not correct.
Option (B),
x = -2 means x < 1
f(x) = 2x will be applicable.
f(-2) = 2(-2) = -4
Therefore, f(-2) = 4 is not correct.
Option (C)
For x = 1,
f(1) = 5
Therefore, f(1) = 5 is the correct option.
Option (D)
x = 2 means x > 1 and the function defined will be,
f(x) = x²
f(2) = 2²
= 4
Therefore, f(2) = 4 will be the correct option.
Options (C) and (D) will be the answer.
Knowing the volume of a 3-D shape is extremely when deciding what materials to use and how much of them to use. When you know the volume of the different designs is helpful when deciding which material costs less to use but still meets requirements. For example, if you were trying to decide what material to fill your product with, and say the volume of your product is 36^3. You narrow things down to two products, one costing $54 to fill the entire thing. The other costing $60. Because you have the volume, it will be easy to decide which is better based off of the price per square inch. If you didn't have the volume. You would have to make an estimate and potentially make a bad business decision.
Hope this helps! I apologize for my long response
