How do you find the area (without graphing) of rectangles when only the points are given?

[Anonymous]

These are the points:

A. (-1,3)(-1,2)(9,2)(9,3)

B. (3,7)(5,7)(5,-3)(3,-3)

C. (-52,73)(96,73)(96,1483)(-52,1483)

[slipslender]

A.

(-1,3)(-1,2)(9,2)(9,3)

=

(x1,y1)(x2,y2)(x3,y3)(x4,y4)

you solve these problems by finding the length and width of the rectangle and then multiplying.

absolute value of (x3-x1) = 9 - -1 = 10

absolute value of (y4-y2) = 3 - 2 = 1

10 x 1 = 10 square units

B.

(3,7)(5,7)(5,-3)(3,-3)

=

(x1,y1)(x2,y2)(x3,y3)(x4,y4)

absolute value of (x3-x1) = 5 - 3 = 2

absolute value of (y4-y2) = -3 - 7 = -10 ---> 10 (absolute value makes it positive)

2 x 10 = 20 square units

you can apply that formula to C.

remember, this formula works because the problem is arranged in such a way that x1 and x2 are the SAME VALUE as is x3 and x4 -OR- that y1 and y2 are the same value as is y3 and y4. you can see that for problem A, x1 and x2 are both -1 and that x3 and x4 are both -9. in problem B, y1 and y2 are both 7 and y3 and y4 are both -3. just keep that in mind. so if you're teacher gives you a problem like:

D.

(-1,3)(9,2)(9,3)(-1,2) MAKE SURE YOU REORGANIZE IT LIKE THIS:

(-1,3)(-1,2)(9,2)(9,3) and THEN you can apply the formula.

hope this makes sense :)

[Voltaire]

You made that way more complicated than it needs to be. Like obscenely so.

[Asker]

sh*t no wonder I suck at math because I swear this is in a different language lol...thanks though:)

[slipslender]

@QA: I know I made it seem sort of complicated, I wish I could have shown you in person. but does the formula make sense? it's really basic... I tend to just visualize plotting the points in my head, but I wasn't sure if you were good with that, so I just came up with this formula that will work for all problems of this type... please tell me it sort of makes sense? if it doesn't, tell me what you're confused with and I'll try to break it down for you. :)

[Voltaire]

Here.

Two points will have the same x value. Find the distance between their y values, that's one side.

Two points will have the same y value, find the distance between their x values. That's the other.

Multiply and win.

[slipslender]

there you go.

[Voltaire]

3 sentences > Math gobbledy gook

Brevity is the soul of wit, strumpet.

[Asker]

@Voltaire: thanks for dumbing it down for me:) I understand it now:)

and now when I look at your answer slipslender, it makes more sense..but is still confusing lol :p

[slipslender]

yep, sorry for the confusion. I just wanted to give you something you could apply to all problems, but I did make it more difficult than necessary, it wasn't my intention... :)

[Asker]

lol my last question for you is, how did you simplify the last equation?

[slipslender]

do you mean problem C? the fake problem D I put up?

[Asker]

lol I thought you simplified C somehow lol

[slipslender]

no lol, I just meant, try out what I did for A and B for problem C. use what Voltaire said...that's the easier way of doing it.

[Asker]

ok..thanks lol :) your a life saver:)

[slipslender]

haha, nah, I think Voltaire was in this case. but thanks for BA :)

[xxxmegan]

LMAOOOOO! Using GaG for math homework! This is awesome! Love it!

[Asker]

hey...people will help lol :p

[Voltaire]

Find how long and wide it is and multiply them together.

A is a 10x1 rectangle. Do L x W to find the area.

[Asker]

thanks

[dudeman]

you punch the numbers till they give you the answer

[Anonymous]

Use the distance formula if you have learned it, that's what my teacher has taught us...

[Asker]

nope I'm doing homework that hasn't been assigned yet because I don't want to do geometry the rest of the week lol

[Opinion Owner]

I do that too, but sometimes if you get stuck on something explain to the teacher that your working ahead and see if they can help you out with the work...

[Asker]

ha my teacher would be pissed because we are supose to "learn as a class" but I would like to see her carrying around a backpack to all my classes because every teacher wants us to have a stupid binder and a book that weighs 20lbs lol...if I can get ahead and not carry another binder and book then I will do it :p I thought I was the only one that did this lol :)

[Opinion Owner]

I do it just so I can go home and be lazy and not pay attention in class.

[Asker]

haha...I hate school I already have an essay due next week and 2 test Monday (one is a practice for SATs), a german 2 test tomorrow (I will most likely fail that lol) and a projest/speech due Friday and a bunch of other stuff...plus I need to study cause I'm taking the temp. test this week to drive:/ oh well lol

[THAT-1-guy]

do length times width

[Asker]

yes but how do you find it with points for a graph?

[THAT-1-guy]

i have never had to do that before sorry... try googling it

[Asker]

it's ok:) thanks anyways

[THAT-1-guy]

Your welcome sory I couldn't help