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GEOMETRY. 6.5 Rhombi and Squares. A rhombus is a parallelogram with four congruent sides. Diagonals of a Rhombus. Theorem 6.15: A parallelogram is a rhombus if and only if its diagonals are perpendicular.
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GEOMETRY 6.5 Rhombi and Squares
A rhombus is a parallelogram with four congruent sides
Diagonals of a Rhombus • Theorem 6.15: A parallelogram is a rhombus if and only if its diagonals are perpendicular.
Theorem 6.16: A parallelogram is a rhombus if and only if each diagonal bisects a pair of opposite angles.
Theorem 6.19 • If one pair of consecutive sides of a parallelogram are congruent, then the parallelogram is a rhombus.
Example 1 A B ABCD is a rhombus. (6x + 30)° Find x, y, and z. 18 2z-2 (7y -2)° (3y +10)° D C
A square is a parallelogram with 4 congruent sides and 4 right angles.
Theorem 6.20 • If a parallelogram is a rhombus and a rectangle, then it is a square.
Example 2 • ABCD is a square.
Venn Diagram parallelograms rhombi rectangles squares
Example 3 • Determine if parallelogram QRST is a rhombus, rectangle, or square. Q(-2,-1), R(-1,2), S(4,1), T(3,-2)
Homework Worksheet and… Page 431: (7-12, 23-33, 55-60) all