What information would you need to find the perimeter of to the right with vertices A(-3,1), B (-1,3) and C(3,1)?

Question

What information would you need to find the perimeter of    to the right with vertices A(-3,1), B (-1,3) and C(3,1)?

anonymous · Answer

attachment

anonymous · Answer

in between "of" and "to" is rectangle ABC

mertsj · Answer

The lengths of the sides.  That's the way you find perimeter...by adding the sides.

anonymous · Answer

how do i know what the sides are?

whpalmer4 · Answer

you can use the distance formula to find the length of each side — just compute the distance between points A and B, points B and C, points C and A.  Add the 3 distances to get the perimeter.

$$d =\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$$

whpalmer4 · Answer

[formula for distance between two points $(x_1,y_1), (x_2,y_2)$]

anonymous · Answer

im sorry i dont quite understand that

whpalmer4 · Answer

okay, let point A be $(x_1,y_1)$ and point B be $(x_2,y_2)$.  Put those coordinates in the distance formula to get the distance between A and B.  Do you see how to do that?

anonymous · Answer

somewhat

whpalmer4 · Answer

if you have a question, speak up...

whpalmer4 · Answer

otherwise, why don't you do that right now and tell me what you get, so we can debug the process if you get the wrong answer.

whpalmer4 · Answer

point A is (-3,1) and point B is (-1,3) so $x_1 = -3, y_1 = 1, x_2 = -1, y_2 = 3$
plug those values into the formula...

anonymous · Answer

32?

whpalmer4 · Answer

hmm.  go look at the diagram.  does seem like a reasonable distance between those points?

anonymous · Answer

i dont know

whpalmer4 · Answer

count!  is it 32 square lengths from A to B?

whpalmer4 · Answer

no, it's not.

show me your work for how you got 32...

anonymous · Answer

i subtracted (-3,1) and got -4 then squared it to 16 then the exact same with the other side

anonymous · Answer

and then added the 16s together to get 32

anonymous · Answer

aaaaaaaaaaand then i forgot to do the thing

whpalmer4 · Answer

no.

point A is (-3,1) and point B is (-1,3) so $x_1=−3,y_1=1,x_2=−1,y_2=3$
plug those values into the formula...

formula is $$d = \sqrt{(x_2-x_1)^2+(y_2-y_1)^2}$$

what is $-3-(-1)$?
what is $3-1$?

whpalmer4 · Answer

we're using the Pythagorean theorem to find the distance between A and B.  the two sides of the triangles are found by $(x_2-x_1)$ and $(y_2-y_1)$ as seen in the picture:|dw:1373379561676:dw|