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Page 1 RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) EXERCISE 17. 1 2 . 7 1 : O N S E G A P 1 1. Given below is a parallelogram ABCD. Complete each statement along with the definition or property used. (i) AD = (ii) ?DCB = (iii) OC = (iv) ?DAB + ?CDA = Solution: (i) AD = BC. Because, diagonals bisect each other in a parallelogram. (ii) ?DCB = ?BAD. Because, alternate interior angles are equal. (iii) OC = OA. Because, diagonals bisect each other in a parallelogram. (iv) ?DAB+ ?CDA = 180°. Because sum of adjacent angles in a parallelogram is 180°. 2. The following figures are parallelograms. Find the degree values of the unknowns x, y, z. Page 2 RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) EXERCISE 17. 1 2 . 7 1 : O N S E G A P 1 1. Given below is a parallelogram ABCD. Complete each statement along with the definition or property used. (i) AD = (ii) ?DCB = (iii) OC = (iv) ?DAB + ?CDA = Solution: (i) AD = BC. Because, diagonals bisect each other in a parallelogram. (ii) ?DCB = ?BAD. Because, alternate interior angles are equal. (iii) OC = OA. Because, diagonals bisect each other in a parallelogram. (iv) ?DAB+ ?CDA = 180°. Because sum of adjacent angles in a parallelogram is 180°. 2. The following figures are parallelograms. Find the degree values of the unknowns x, y, z. RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) Solution: (i) ?ABC = ?y = 100 o (opposite angles are equal in a parallelogram) ?x + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?x + 100 o = 180 o ?x = 180 o - 100 o = 80 o ? ?x = 80 o ?y = 100 o ?z = 80 o (opposite angles are equal in a parallelogram) (ii) ?RSP + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?y + 50 o = 180 o ?y = 180 o - 50 o = 130 o ? ?x = ?y = 130 o (opposite angles are equal in a parallelogram) ?RSP = ?RQP = 50 o (opposite angles are equal in a parallelogram) ?RQP + ?z = 180 o (linear pair) 50 o + ?z = 180 o ?z = 180 o – 50 o = 130 o ? ?x = 130 o ?y = 130 o ?z = 130 o (iii) In ?PMN ?NPM + ?NMP + ?MNP = 180° [Sum of all the angles of a triangle is 180°] Page 3 RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) EXERCISE 17. 1 2 . 7 1 : O N S E G A P 1 1. Given below is a parallelogram ABCD. Complete each statement along with the definition or property used. (i) AD = (ii) ?DCB = (iii) OC = (iv) ?DAB + ?CDA = Solution: (i) AD = BC. Because, diagonals bisect each other in a parallelogram. (ii) ?DCB = ?BAD. Because, alternate interior angles are equal. (iii) OC = OA. Because, diagonals bisect each other in a parallelogram. (iv) ?DAB+ ?CDA = 180°. Because sum of adjacent angles in a parallelogram is 180°. 2. The following figures are parallelograms. Find the degree values of the unknowns x, y, z. RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) Solution: (i) ?ABC = ?y = 100 o (opposite angles are equal in a parallelogram) ?x + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?x + 100 o = 180 o ?x = 180 o - 100 o = 80 o ? ?x = 80 o ?y = 100 o ?z = 80 o (opposite angles are equal in a parallelogram) (ii) ?RSP + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?y + 50 o = 180 o ?y = 180 o - 50 o = 130 o ? ?x = ?y = 130 o (opposite angles are equal in a parallelogram) ?RSP = ?RQP = 50 o (opposite angles are equal in a parallelogram) ?RQP + ?z = 180 o (linear pair) 50 o + ?z = 180 o ?z = 180 o – 50 o = 130 o ? ?x = 130 o ?y = 130 o ?z = 130 o (iii) In ?PMN ?NPM + ?NMP + ?MNP = 180° [Sum of all the angles of a triangle is 180°] RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) 30° + 90° + ?z = 180° ?z = 180°-120° = 60° ?y = ?z = 60° [opposite angles are equal in a parallelogram] ?z = 180°-120° [sum of the adjacent angles is equal to 180° in a parallelogram] ?z = 60° ?z + ?LMN = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] 60° + 90°+ ?x = 180° ?x = 180°-150° ?x = 30° ? ?x = 30 o ?y = 60 o ?z = 60 o (iv) ?x = 90° [vertically opposite angles are equal] In ?DOC ?x + ?y + 30° = 180° [Sum of all the angles of a triangle is 180°] 90° + 30° + ?y = 180° ?y = 180°-120° ?y = 60° ?y = ?z = 60° [alternate interior angles are equal] ? ?x = 90 o ?y = 60 o ?z = 60 o (v) ?x + ?POR = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] ?x + 80° = 180° ?x = 180°-80° ?x = 100° ?y = 80° [opposite angles are equal in a parallelogram] ?SRQ = ?x = 100° ?SRQ + ?z = 180° [Linear pair] 100° + ?z = 180° ?z = 180°-100° ?z = 80° ? ?x = 100 o ?y = 80 o ?z = 80 o (vi) ?y = 112° [In a parallelogram opposite angles are equal] ?y + ?VUT = 180° [In a parallelogram sum of the adjacent angles is equal to 180°] ?z + 40° + 112° = 180° ?z = 180°-152° ?z = 28° ?z = ?x = 28° [alternate interior angles are equal] Page 4 RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) EXERCISE 17. 1 2 . 7 1 : O N S E G A P 1 1. Given below is a parallelogram ABCD. Complete each statement along with the definition or property used. (i) AD = (ii) ?DCB = (iii) OC = (iv) ?DAB + ?CDA = Solution: (i) AD = BC. Because, diagonals bisect each other in a parallelogram. (ii) ?DCB = ?BAD. Because, alternate interior angles are equal. (iii) OC = OA. Because, diagonals bisect each other in a parallelogram. (iv) ?DAB+ ?CDA = 180°. Because sum of adjacent angles in a parallelogram is 180°. 2. The following figures are parallelograms. Find the degree values of the unknowns x, y, z. RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) Solution: (i) ?ABC = ?y = 100 o (opposite angles are equal in a parallelogram) ?x + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?x + 100 o = 180 o ?x = 180 o - 100 o = 80 o ? ?x = 80 o ?y = 100 o ?z = 80 o (opposite angles are equal in a parallelogram) (ii) ?RSP + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?y + 50 o = 180 o ?y = 180 o - 50 o = 130 o ? ?x = ?y = 130 o (opposite angles are equal in a parallelogram) ?RSP = ?RQP = 50 o (opposite angles are equal in a parallelogram) ?RQP + ?z = 180 o (linear pair) 50 o + ?z = 180 o ?z = 180 o – 50 o = 130 o ? ?x = 130 o ?y = 130 o ?z = 130 o (iii) In ?PMN ?NPM + ?NMP + ?MNP = 180° [Sum of all the angles of a triangle is 180°] RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) 30° + 90° + ?z = 180° ?z = 180°-120° = 60° ?y = ?z = 60° [opposite angles are equal in a parallelogram] ?z = 180°-120° [sum of the adjacent angles is equal to 180° in a parallelogram] ?z = 60° ?z + ?LMN = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] 60° + 90°+ ?x = 180° ?x = 180°-150° ?x = 30° ? ?x = 30 o ?y = 60 o ?z = 60 o (iv) ?x = 90° [vertically opposite angles are equal] In ?DOC ?x + ?y + 30° = 180° [Sum of all the angles of a triangle is 180°] 90° + 30° + ?y = 180° ?y = 180°-120° ?y = 60° ?y = ?z = 60° [alternate interior angles are equal] ? ?x = 90 o ?y = 60 o ?z = 60 o (v) ?x + ?POR = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] ?x + 80° = 180° ?x = 180°-80° ?x = 100° ?y = 80° [opposite angles are equal in a parallelogram] ?SRQ = ?x = 100° ?SRQ + ?z = 180° [Linear pair] 100° + ?z = 180° ?z = 180°-100° ?z = 80° ? ?x = 100 o ?y = 80 o ?z = 80 o (vi) ?y = 112° [In a parallelogram opposite angles are equal] ?y + ?VUT = 180° [In a parallelogram sum of the adjacent angles is equal to 180°] ?z + 40° + 112° = 180° ?z = 180°-152° ?z = 28° ?z = ?x = 28° [alternate interior angles are equal] RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) ? ?x = 28 o ?y = 112 o ?z = 28 o 3. Can the following figures be parallelograms? Justify your answer. Solution: (i) No, opposite angles are equal in a parallelogram. (ii) Yes, opposite sides are equal and parallel in a parallelogram. (iii) No, diagonals bisect each other in a parallelogram. 4. In the adjacent figure HOPE is a parallelogram. Find the angle measures x, y and z. State the geometrical truths you use to find them. Solution: We know that ?POH + 70° = 180° [Linear pair] ?POH = 180°-70° ?POH = 110° Page 5 RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) EXERCISE 17. 1 2 . 7 1 : O N S E G A P 1 1. Given below is a parallelogram ABCD. Complete each statement along with the definition or property used. (i) AD = (ii) ?DCB = (iii) OC = (iv) ?DAB + ?CDA = Solution: (i) AD = BC. Because, diagonals bisect each other in a parallelogram. (ii) ?DCB = ?BAD. Because, alternate interior angles are equal. (iii) OC = OA. Because, diagonals bisect each other in a parallelogram. (iv) ?DAB+ ?CDA = 180°. Because sum of adjacent angles in a parallelogram is 180°. 2. The following figures are parallelograms. Find the degree values of the unknowns x, y, z. RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) Solution: (i) ?ABC = ?y = 100 o (opposite angles are equal in a parallelogram) ?x + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?x + 100 o = 180 o ?x = 180 o - 100 o = 80 o ? ?x = 80 o ?y = 100 o ?z = 80 o (opposite angles are equal in a parallelogram) (ii) ?RSP + ?y = 180 o (sum of adjacent angles is = 180 o in a parallelogram) ?y + 50 o = 180 o ?y = 180 o - 50 o = 130 o ? ?x = ?y = 130 o (opposite angles are equal in a parallelogram) ?RSP = ?RQP = 50 o (opposite angles are equal in a parallelogram) ?RQP + ?z = 180 o (linear pair) 50 o + ?z = 180 o ?z = 180 o – 50 o = 130 o ? ?x = 130 o ?y = 130 o ?z = 130 o (iii) In ?PMN ?NPM + ?NMP + ?MNP = 180° [Sum of all the angles of a triangle is 180°] RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) 30° + 90° + ?z = 180° ?z = 180°-120° = 60° ?y = ?z = 60° [opposite angles are equal in a parallelogram] ?z = 180°-120° [sum of the adjacent angles is equal to 180° in a parallelogram] ?z = 60° ?z + ?LMN = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] 60° + 90°+ ?x = 180° ?x = 180°-150° ?x = 30° ? ?x = 30 o ?y = 60 o ?z = 60 o (iv) ?x = 90° [vertically opposite angles are equal] In ?DOC ?x + ?y + 30° = 180° [Sum of all the angles of a triangle is 180°] 90° + 30° + ?y = 180° ?y = 180°-120° ?y = 60° ?y = ?z = 60° [alternate interior angles are equal] ? ?x = 90 o ?y = 60 o ?z = 60 o (v) ?x + ?POR = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] ?x + 80° = 180° ?x = 180°-80° ?x = 100° ?y = 80° [opposite angles are equal in a parallelogram] ?SRQ = ?x = 100° ?SRQ + ?z = 180° [Linear pair] 100° + ?z = 180° ?z = 180°-100° ?z = 80° ? ?x = 100 o ?y = 80 o ?z = 80 o (vi) ?y = 112° [In a parallelogram opposite angles are equal] ?y + ?VUT = 180° [In a parallelogram sum of the adjacent angles is equal to 180°] ?z + 40° + 112° = 180° ?z = 180°-152° ?z = 28° ?z = ?x = 28° [alternate interior angles are equal] RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) ? ?x = 28 o ?y = 112 o ?z = 28 o 3. Can the following figures be parallelograms? Justify your answer. Solution: (i) No, opposite angles are equal in a parallelogram. (ii) Yes, opposite sides are equal and parallel in a parallelogram. (iii) No, diagonals bisect each other in a parallelogram. 4. In the adjacent figure HOPE is a parallelogram. Find the angle measures x, y and z. State the geometrical truths you use to find them. Solution: We know that ?POH + 70° = 180° [Linear pair] ?POH = 180°-70° ?POH = 110° RD Sharma Solutions for Class 8 Maths Chapter 17 – Understanding Shapes – III (Special Types of Quadrilaterals) ?POH = ?x = 110° [opposite angles are equal in a parallelogram] ?x + ?z + 40° = 180° [sum of the adjacent angles is equal to 180° in a parallelogram] 110° + ?z + 40° = 180° ?z = 180° - 150° ?z = 30° ?z + ?y = 70° ?y + 30° = 70° ?y = 70°- 30° ?y = 40° 5. In the following figures GUNS and RUNS are parallelograms. Find x and y. Solution: (i) 3y – 1 = 26 [opposite sides are of equal length in a parallelogram] 3y = 26 + 1 y = 27/3 y = 9 3x = 18 [opposite sides are of equal length in a parallelogram] x = 18/3 x = 6 ? x = 6 and y = 9 (ii) y – 7 = 20 [diagonals bisect each other in a parallelogram] y = 20 + 7 y = 27 x - y = 16 [diagonals bisect each other in a parallelogram] x -27 = 16Read More
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