Which transformation will always map a parallelogram onto itself?
o a.
a 90° rotation about its center
a reflection across one of its diagonals
ob.
o c.
a 180° rotation about its center
od.
a reflection across a line joining the midpoints of opposite sides

C..

Step-by-step explanation:

A rotation of 180 degrees about the center of the parallelogram will  do this.

geometry: triangles

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call the larger triangle abc

then the smaller triangle cde is similar to abc (all angles are equal, aaa).  

ab is the side that is 36, and we wish to find de, the side corresponding to ab

area_cde = area_abc - area_cde --> area_abc / area_cde = 2

let x=length of de

ratio of areas = (ratio of sides)^2

+2+=+%2836%2fx%29%5e2+

+2+=+1296%2fx%5e2+

++x%5e2+=+1296%2f2+=+648+

25.45584

a)(x-2)^2+(y-1)^2=9

step-by-step explanation:

(picture explains)