Good evening, I apologise if I am interrupting your time, how do I calculate the Diagonals of parallelograms and its height? In advance thank you very much.
#Geometry homework
glacial blade
proven harborBOT
limpid robin
can you show a specific question?
glacial blade
It is in Serbian, but I will translate it.
Find the length of sides and Diagonals of parallelogram ABCD if A(0,0) B(8,4) C(6,8) D(-2,4).
limpid robin
ok, you found the lengths of all the sides?
limpid robin
ok, do you know the formula for the length of diagonal using that information?
glacial blade
oh, is this a rectangle?
No, it's parallelogram.
limpid robin
rectangles are parallelograms.
glacial blade
Oops.
glacial blade
rectangles are parallelograms.
Well yes.
limpid robin
so what are the edge lengths?
glacial blade
I only have length of sides.
limpid robin
That's what I'm asking 
glacial blade
Aha.
limpid robin
Do you know how to test if four points form a rectangle
limpid robin
Find the length of sides and Diagonals of parallelogram ABCD if A(0,0) B(8,4) C(...
according to this
glacial blade
A is a point
A is one side. B is another.
If you got confused, then mark it with a and b.
limpid robin
here's some labels for your parallelogram
here's what you want to do to determine if it is a rectangle
(there are a few ways but this is one of them)
Find the distance between (0,0) and (6,8) using distance formula
call it y'
then determine if c^2+d^2=y'^2. If this is the case, then y' = y and that forms a right triangle
making this a rectangle
and also giving you one of the diagonal lengths
you could do it instead for x which would be easier since finding the distance between (-2,4) and (8,4) takes like two seconds
either way
another way would be to use trig
another way would be to find the slopes of the red lines and take product
in any event let me know if that works for you
glacial blade
Thank you very much, it is so simple 😂.
I have another exercise if you don't mind.
limpid robin
sure, I may have to go soon but ill see if i can help
glacial blade
Find the length of centroid straight line of triangle ABC if A(-8, - 2) B(0, - 4) C(8,6).
Hello?
limpid robin
uhhh ok
you know the definition of centroid?
the way I would do it is probably overcomplicated if you know the formula
glacial blade
Point of the object.
limpid robin
however I do not remember the formula, i can look it up
glacial blade
Yeah.
limpid robin
its the point in the "center,", i.e. the intersection of the 3 bisecting lines
glacial blade
Yes, yes.
limpid robin
oh I remember the formula now
glacial blade
Aha.
limpid robin
yeah so you just average all the coordinates
glacial blade
But I need for all three sides.
limpid robin
hm?
no like you have the 3 x coordinates for the points
average those and you get the x coordinate for the centroid
same for the y coordinate
glacial blade
In Serbian we call it "težište".
But in exercise it is needed for all three sides.
Centroid for side A, centroid for side B, centroid for side C.