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Learn and apply properties of rectangles, including parallel sides, congruent angles, and congruent diagonals. Determine if given quadrilaterals are rectangles. Practice exercises included.
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Geometry Lesson 6 – 4 Rectangles Objective: Recognize and apply properties of rectangles. Determine whether parallelograms are rectangles.
Rectangle • A parallelogram with 4 right angles. • Opposite sides are parallel and congruent • Opposite angles are congruent (right) • Consecutive angles are supplementary • Diagonals bisect each other • NEW: Diagonals are congruent.
Theorem • Diagonals of a Rectangle • If a parallelogram is a rectangle, then its diagonals are congruent.
PR = QS • A rectangular park has two walking paths as shown. If PS = 180 meters and PR = 200 meters, find QT and RS. QS = 200 QT = (1/2)(QS) 180 200 QT = (1/2)(200) QT = 100 (PS)2 + (SR)2 = (PR)2 (SR)2 = 7600 (180)2 + (SR)2 = (200)2 32400 + (SR)2 = 40000
64 64 • If 26 26 26 64 64
Quadrilateral JKLM is a rectangle. If measure of angle KJL is 2x + 4 and measure of angle JLK is 7x + 5, find x. (2x + 4)o (7x + 5)o 2x + 4 + 7x + 5 = 90 9x + 9 = 90 9x = 81 x = 9
Quadrilateral JKLM is a rectangle. If JP = 3y – 5 and MK = 5y + 1, find y. 3y - 5 5y + 1 2(JP) = MK 2(3y – 5) = 5y + 1 6y – 10 = 5y + 1 y = 11
Theorem • Theorem 6.14 • If the diagonals of a parallelogram are congruent, then the parallelogram is a rectangle.
Quadrilateral PQRS has vertices P(-5, 3), R(-1, -4) Q(1, -1) and S (-7, 0). Determine whether PQRS is a rectangle by using the distance formula. First figure out if the quad is a parallelogram By doing one of the tests. Either prove opp sides are congruent or one set Of opp sides is parallel and congruent. Cont…
Figure out if the parallelogram is a rectangle: Diagonals of a rectangle are congruent. Quadrilateral PQRS is a rectangle.
Quadrilateral JKLM has vertices J(-10, 2) K(-8,-6) L(5, -3) M(2, 5) • Determine whether JKLM is a rectangle using the Slope formula. To be a rectangle, consecutive sides must be perpendicular (opp. reciprocals) Since the slopes of consecutive sides are not opposite reciprocals the figure is not a rectangle.
Homework • Pg. 422 1 – 9 all, 10 – 18 E, 22 – 30 E, 50 – 60 E