180 likes | 205 Views
6.3 Rectangles. Properties of Special Parallelograms. In this lesson, you will study a special types of parallelograms: rectangles. A rectangle is a parallelogram with four right angles. Properties of Rectangles. Practice:. Practice:. 2x + y = 36 x – y = 9 Solving System of Equations
E N D
Properties of Special Parallelograms • In this lesson, you will study a special types of parallelograms: rectangles A rectangle is a parallelogram with four right angles.
Practice: 2x + y = 36 x – y = 9 Solving System of Equations 3x = 45 X = 15 Y = 6
Practice: x + 11 = y x + 2 = y – 3x Solving System of Equations 9 = 3x X = 3 Y = 14
Practice: 4x + 8 + 5x – 8 = 90 Solving Equation 9x = 90 X = 10
Practice: x = 6x - 8 Solving Equation - 5 x = -8 X = 1.6
Properties of Special Parallelograms • In this lesson, you will study two special types of parallelograms: rhombi and squares. A square is a parallelogram with four congruent sides and four right angles. A rhombus is a parallelogram with four congruent sides
Take note: • Rhombus: A quadrilateral is a rhombus if and only if it has four congruent sides. • Rectangle: A quadrilateral is a rectangle if and only if it has four right angles. • Square: A quadrilateral is a square if and only if it is a rhombus and a rectangle.
Ex. 3: Using properties of a Rhombus • In the diagram at the right, PQRS is a rhombus. What is the value of y? All four sides of a rhombus are ≅, so RS = PS. 5y – 6 = 2y + 3 5y = 2y + 9 3y = 9 y = 3
The following theorems are about diagonals of rhombi and rectangles. A parallelogram is a rhombus if and only if its diagonals are perpendicular. ABCD is a rhombus if and only if AC BD. Using diagonals of special parallelograms
A parallelogram is a rhombus if and only if each diagonal bisects a pair of opposite angles. ABCD is a rhombus if and only if AC bisects DAB and BCD and BD bisects ADC and CBA. Using diagonals of special parallelograms
Find the lengths of the sides of ABCD. Use the distance formula (See – you’re never going to get rid of this) AB=√(b – 0)2 + (0 – a)2 = √b2 + a2 BC= √(0 - b)2 + (– a - 0)2 = √b2 + a2 CD= √(- b – 0)2 + [0 - (– a)]2 = √b2 + a2 DA= √[(0 – (- b)]2 + (a – 0)2 = √b2 + a2 Given: ABCD is a parallelogram, AC BD.Prove: ABCD is a rhombus A(0, a) D(- b, 0) B(b, 0) C(0, - a) All the side lengths are equal, so ABCD is a rhombus.
Practice: 4x- 3 = 18 + x 3 x – 3 = 18 3x = 21 X = 7