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)
Answer:
it is -40
Step-by-step explanation:
yes yes right????
Answer:
Solution
-1
f
x=
1
-X+
2
Step-by-step explanation:
f(x=2x-7
Solving Steps
y=2x-7
Interchange the variables
x=2y-7
Swap the sides
2y-7=X
Move the constant to the right
2y=X+7
Divide both sides
1
y=
>+*.
7
2
Solution
-1
f
x=
1
-X+
2
It representes the original cost
A=P(1+r)^t
P=present amount
t=time
r=rate
A=final amount
afer 5 years
t=5
A=799(1.03)^5
A=926.26 after 5 years
answer is last option:
<span>799 represents the total value of the painting; the painting will be worth $926 after 5 years
</span>
Answer:
16.5 =x
Step-by-step explanation:
Since this is a right triangle, we can us trig functions
tan theta = opp side / adjacent
tan 70 = x /6
Multiply each side by 6
6 tan 70 = x
16.48486452 =x
To the nearest tenth
16.5 =x
