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PAGE: 352 | SET: Exercises | PROBLEM: 6 |

Explore: Plot the vertices on a coordinate plane.
Plan:
If the diagonals are perpendicular, then ABCD is either a rhombus or a square.
The diagonals of a rectangle are congruent. If the diagonals are congruent and perpendicular, then ABCD is a square.
Solve:
Use the Distance Formula to compare the lengths of the diagonals.
The distance formula is .
(Substitute
)
(Simplify)
(Substitute
)
(Simplify)
Use slope to determine whether the diagonals are perpendicular.
The slope formula is .
Slope of (Substitute
)
Slope of (Substitute
)
Since the slope of is the negative reciprocal of the slope of
, the diagonals are perpendicular.
and
have the same measure, so the diagonals are congruent. ABCD is a rhombus, a rectangle, and a square.
ABCD is a rhombus, a rectangle, and a square.

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