Triangle ABC maps to triangle A′B′C′ by a 90∘ rotation counterclockwise about the origin. If AB=61 units, BC=11 units, and AC=60 units, what is the length of A′C′?
11 units
61 units
90 units
60 units

60 Units

Step-by-step explanation:

The length of AC does not change. Since the translation is a rotation, nothing about the size of the triangle should change. Meaning A'B'C' is still 60 units in length.

only 10/60 isn't equivalent

hope this : )

for the friend request.

when a figure, such as triangle (xyz) is reflected over the line y = x to create x'y'z' the x-coordinates and y-coordinates of the original image (pre-image) will be reversed for the image. (e.g., (x, y) > (y, x)) this means that the pre-image position of the x- and y-coordinates switch places which in turn provides a mirror like image of the original xyz.  

i notice that when i draw a line segment from x to x', that the points are parallel from each other -- they are exactly across from each other and do not intersect with any other points.  

yes, think i would see the same characteristic if you drew the line segment connecting y with the reflecting line and then y' with the reflecting line because of the essence of reflections. because it is a mirror image, each point was effected the same way which leads me to conclude that they same would apply to y and y'.