Question

The coordinates of three vertices of square ABCD are A(−212,112),B(−212,−3), and C(2,112).

When point D is placed on this square, what will the perimeter of the square be?
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Answer 1

P=760

Explanation:

Three of the coordinates of the square ABCD are A(-212,112) B(-212,-3) C(2,112). The image below shows the square is not ABCD but ABDC. In fact, this is not a square, as we'll prove later.

Note the x-coordinate of A and B are the same. It means this side is parallel to the y-axis. Also, the y-coordinate of A and C are the same, meaning this side is parallel to the x-axis. The missing point D should have the same x-coordinate as C and y-coordinate as B, i.e. D=(2,-3).

This shape has sides that are parallel to both axes.

To calculate the perimeter we find the length of two sides.

The distance from A to B is the difference between their y-axis:

w=112-(-3)=115

The distance from A to C is the difference between their x-axis:

l=2-(-212)=215

It's evident this is not a square but a rectangle. The perimeter is

P=2w+2l=330+430

P=760