7.4 Properties of Special Parallelograms OBJ: Students will be able to use properties of special parallelograms and diagonals of special parallelograms.
Do Now
Rhombus A parallelogram with four congruent sides.
Rectangle A parallelogram with four right angles.
Square A parallelogram with four congruent sides and four right angles.
Rhombus Corollary A quadrilateral is a rhombus if and only if it has four congruent sides.
Rectangle Corollary A quadrilateral is a rectangle if and only if it has four right angles.
Square Corollary A quadrilateral is a square if and only if it is a rhombus and a rectangle.
1. For any rectangle ABCD, decide whether the statement is always or sometimes true. Explain your reasoning. a. AB = BC b. AB = CB
2. For any square JKLM, is it always or sometimes true that. Explain your reasoning.
Do Now What classifies a parallelogram as a rhombus, rectangle and square? i.e. what characteristics do each have.
Rhombus Diagonals Theorem A parallelogram is a rhombus if and only if its diagonals are perpendicular.
Rhombus Opposite Angles Theorem A parallelogram is a rhombus if and only if each diagonal bisects a pair of opposite angles.
3. Find the measures of the numbered angles in rhombus ABCD.
4. Find the measures of the numbered angles in rhombus DEFG.
Rectangle Diagonals Theorem A parallelogram is a rectangle if and only if its diagonals are congruent.
5. In rectangle QRST, QS= 5x – 31 and RT = 2x Find the lengths of the diagonals of QRST.
HW Pg. 393 #3,5, 13-16, odds