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)
Complete Question
The complete question is shown on the first uploaded image
Answer:
The first option is the correct option
Step-by-step explanation:
From the question w are told that
The value of shares for A&D in 2 years is 
$150
The value of share for peer comms Ltd is 
$275
The number of more share that you can buy fro A&D compared to peers comms Ltd is
$125
Answer:
yes it is a function
the domain is (-3, 8]
the range looks like (-5, 2.5]
Step-by-step explanation:
using the vertical line test, you can find that it is a function
the domain is all the x values between -3 and 8. -3 is not included since there is an open circle
The range is all the y values
Answer:
You keep adding 15.
Step-by-step explanation:
5+15=20
20+15=35
35+15=50
50+15=65
Answer:
b
Step-by-step explanation:
