1. BY GROUP THREE

2. Rhombus MEANING In Indonesian, rhombuses called belah ketupat. Exactly, rhombuses like kites. But rhombuses has same side. Like this Rhombus : A quadrilateral with four equal angles >

3. Rhombus Properties of Rhombuses These are some of the most important properties of a rhombus. Consider the rhombus ABCD shown in the figure above. 1 - All sides are congruent (equal lengths). length AB = length BC = length CD = length DA = a. 2 - Opposite sides are parallel. AD is parallel to BC and AB is parallel to DC. 3 - The two diagonals are perpendicular. AC is perpendicular to BD. 4 - Opposite internal angles are congruent (equal sizes). internal angle A = internal angle C and internal angle B = internal angle D. 5 - Any two consecutive internal angles are supplementary : they add up to 180 degrees. angle A + angle B = 180 degrees angle B + angle C = 180 degrees angle C + angle D = 180 degrees angle D + angle A = 180 degrees ><

4. Rhombus Area and Perimeter of Rhombuses Measure area of Rhombuses  The area of a rhombus with diagonal d1 and d2, then:  Area = x d1 x d2  Suppose P is perimeter of rhombus with the length of side S, then P = 4 x S d1 d2 ><

5. Rhombus Example If : BD = 10 cm, AC = 14 cm, and AB = 8 cm Count area and perimeter of ABCD! We suppose area = A and perimeter = P A C B D ><

6. Rhombus Solution A = x BD x A C A = x 10 x 14 A = 70 cm 2 P = 4 x AB P = 4 x 8 P = 32 Note : Amount of all angles in rhombus is 360 o ><

7. Rhombus Example If W = 130 o, count X Y, and Z! Solution : WXYZ = 360 o. So, W + Y = 130 + 130 = 260 o. Then 360 o – 260 o = 100 o. And 100 o : 2 = 50 o. Y = 130 o Z = 50 o X = 50 o W X Y Z ><

8. Rhombus Group : a. Abid Famasya A b. Gema Akbar W c. Nikko Caesario MS d. Dhanang Hanis AK e. Siswanto Adi W Top<