G.GPE.B.4: Quadrilaterals in the Coordinate Plane 2

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Regents Exam Questions www.jmap.org Name: 1 In square GEOM, the coordinates of G are (2, 2) and the coordinates of O are ( 4,2). Determine and state the coordinates of vertices E and M. [The use of the set of axes below is optional.] 2 The coordinates of quadrilateral ABCD are A( 1, 5), B(8,2), C(11,13), and D(2,6). Using coordinate geometry, prove that quadrilateral ABCD is a rhombus. [The use of the grid is optional.] 1

Regents Exam Questions www.jmap.org 3 Jim is experimenting with a new drawing program on his computer. He created quadrilateral TEAM with coordinates T( 2,3), E( 5, 4), A(2, 1), and M(5,6). Jim believes that he has created a rhombus but not a square. Prove that Jim is correct. [The use of the grid is optional.] Name: 4 Quadrilateral PQRS has vertices P( 2,3), Q(3,8), R(4,1), and S( 1, 4). Prove that PQRS is a rhombus. Prove that PQRS is not a square. [The use of the set of axes below is optional.] 2

Regents Exam Questions www.jmap.org 5 The vertices of quadrilateral MATH have coordinates M( 4,2), A( 1, 3), T(9,3), and H(6,8). Prove that quadrilateral MATH is a parallelogram. Prove that quadrilateral MATH is a rectangle. [The use of the set of axes below is optional.] Name: 7 The vertices of quadrilateral JKLM have coordinates J( 3,1), K(1, 5), L(7, 2), and M(3,4). Prove that JKLM is a parallelogram. Prove that JKLM is not a rhombus. [The use of the set of axes below is optional.] 6 Given: A( 2,2), B(6,5), C(4,0), D( 4, 3) Prove: ABCD is a parallelogram but not a rectangle. [The use of the grid is optional.] 8 Quadrilateral MATH has coordinates M(1,1), A( 2,5), T(3,5), and H(6,1). Prove that quadrilateral MATH is a rhombus and prove that it is not a square. [The use of the grid is optional.] 3

Regents Exam Questions www.jmap.org 9 Quadrilateral ABCD has vertices A(2,3), B(7,10), C(9,4), and D(4, 3). Prove that ABCD is a parallelogram but not a rhombus. [The use of the grid is optional.] Name: 11 In rhombus MATH, the coordinates of the endpoints of the diagonal MT are M(0, 1) and T(4,6). Write an equation of the line that contains diagonal AH. [Use of the set of axes below is optional.] Using the given information, explain how you know that your line contains diagonal AH. 10 Given: Quadrilateral ABCD has vertices A( 5,6), B(6,6), C(8, 3), and D( 3, 3). Prove: Quadrilateral ABCD is a parallelogram but is neither a rhombus nor a rectangle. [The use of the grid below is optional.] 4

Regents Exam Questions www.jmap.org 12 In the coordinate plane, the vertices of RST are R(6, 1), S(1, 4), and T( 5,6). Prove that RST is a right triangle. State the coordinates of point P such that quadrilateral RSTP is a rectangle. Prove that your quadrilateral RSTP is a rectangle. [The use of the set of axes below is optional.] Name: 13 Ashanti is surveying for a new parking lot shaped like a parallelogram. She knows that three of the vertices of parallelogram ABCD are A(0,0), B(5,2), and C(6,5). Find the coordinates of point D and sketch parallelogram ABCD on the accompanying set of axes. Justify mathematically that the figure you have drawn is a parallelogram. 14 Given: ABC with vertices A( 6, 2), B(2,8), and C(6, 2). AB has midpoint D, BC has midpoint E, and AC has midpoint F. Prove: ADEF is a parallelogram ADEF is not a rhombus [The use of the grid is optional.] 5

Regents Exam Questions www.jmap.org 15 Quadrilateral ABCD with vertices A( 7,4), B( 3,6),C(3,0), and D(1, 8) is graphed on the set of axes below. Quadrilateral MNPQ is formed by joining M, N, P, and Q, the midpoints of AB, BC, CD, and AD, respectively. Prove that quadrilateral MNPQ is a parallelogram. Prove that quadrilateral MNPQ is not a rhombus. Name: 17 Quadrilateral KATE has vertices K(1,5), A(4,7), T(7,3), and E(1, 1). a Prove that KATE is a trapezoid. [The use of the grid is optional.] b Prove that KATE is not an isosceles trapezoid. 16 Given: A(1,6), B(7, 9), C(13,6), and D(3,1) Prove: ABCD is a trapezoid. [The use of the accompanying grid is optional.] 18 The coordinates of quadrilateral JKLM are J(1, 2), K(13,4), L(6,8), and M( 2,4). Prove that quadrilateral JKLM is a trapezoid but not an isosceles trapezoid. [The use of the grid is optional.] 6

Regents Exam Questions www.jmap.org 19 Given: T( 1,1), R(3,4), A(7,2), and P( 1, 4) Prove: TRAP is a trapezoid. TRAP is not an isosceles trapezoid. [The use of the grid is optional.] Name: 20 In the coordinate plane, the vertices of triangle PAT are P( 1, 6), A( 4,5), and T(5, 2). Prove that PAT is an isosceles triangle. [The use of the set of axes below is optional.] State the coordinates of R so that quadrilateral PART is a parallelogram. Prove that quadrilateral PART is a parallelogram. 21 In the accompanying diagram of ABCD, where a b, prove ABCD is an isosceles trapezoid. 7

Answer Section 1 ANS: REF: 011731geo 2 ANS:. To prove that ABCD is a rhombus, show that all sides are congruent using the distance formula: d AB = (8 ( 1)) 2 + (2 ( 5)) 2 = 130. d BC = (11 8) 2 + (13 2) 2 = 130 d CD = (11 2) 2 + (13 6) 2 = 130 d AD = (2 ( 1)) 2 + (6 ( 5)) 2 = 130 REF: 060327b 1

3 ANS:. To prove that TEAM is a rhombus, show that all sides are congruent using the distance formula: d ET = ( 2 ( 5)) 2 + (3 ( 4)) 2 = 58. A square has four right angles. If TEAM is a square, then ET AE, d AM = (2 5) 2 + (( 1) 6) 2 = 58 d AE = ( 5 2) 2 + ( 4 ( 1)) 2 = 58 d MT = ( 2 5) 2 + (3 6) 2 = 58 AE AM, AM AT and MT ET. Lines that are perpendicular have slopes that are opposite reciprocals of each other. The slopes of sides of TEAM are: m ET = 4 3 5 ( 2) = 7 4 ( 1) m 3 AE = 5 2 = 3 Because 7 7 3 and 3 are not 7 m AM = 6 ( 1) 5 2 = 7 m MT = 3 6 3 2 5 = 3 7 opposite reciprocals, consecutive sides of TEAM are not perpendicular, and TEAM is not a square. REF: 010533b 4 ANS: PQ (8 3) 2 + (3 2) 2 = 50 QR (1 8) 2 + (4 3) 2 = 50 RS ( 4 1) 2 + ( 1 4) 2 = 50 PS ( 4 3) 2 + ( 1 2) 2 = 50 PQRS is a rhombus because all sides are congruent. m PQ = 8 3 3 2 = 5 5 = 1 m QR = 1 8 = 7 Because the slopes of adjacent sides are not opposite reciprocals, they are not perpendicular 4 3 and do not form a right angle. Therefore PQRS is not a square. REF: 061735geo 2

5 ANS: m MH = 6 10 = 3 5, m = 6 AT 10 = 3 5, m = 5 MA 3, m = 5 HT ; MH AT and MA HT. 3 MATH is a parallelogram since both sides of opposite sides are parallel. m MA = 5 3, m AT = 3. Since the slopes 5 are negative reciprocals, MA AT and A is a right angle. MATH is a rectangle because it is a parallelogram with a right angle. REF: 081835geo 6 ANS: To prove that ABCD is a parallelogram, show that both pairs of opposite sides of the parallelogram are parallel by showing the opposite sides have the same slope: m AB = 5 2 6 ( 2) = 3 8 m CD = 3 0 4 4 = 3 8 m AD = 3 2 4 ( 2) = 5 2 m BC = 5 0 6 4 = 5 2 A rectangle has four right angles. If ABCD is a rectangle, then AB BC, BC CD, CD AD, and AD AB. Lines that are perpendicular have slopes that are the opposite and reciprocal of each other. Because 3 8 and 5 2 are not opposite reciprocals, the consecutive sides of ABCD are not perpendicular, and ABCD is not a rectangle. REF: 060633b 3

7 ANS: m JM = 1 4 3 3 = 3 6 = 1 2 m = ML = 4 2 3 7 = 6 4 = 3 2 2 5 m LK = 7 1 = 3 6 = 1 2 m KJ = 5 1 1 3 = 6 4 = 3 2 Since both opposite sides have equal slopes and are parallel, JKLM is a parallelogram. JM = ( 3 3) 2 + (1 4) 2 = 45. JM is not congruent to ML, so JKLM is not a rhombus since not all sides ML= (7 3) 2 + ( 2 4) 2 = 52 are congruent. REF: 061438ge 8 ANS: The length of each side of quadrilateral is 5. Since each side is congruent, quadrilateral MATH is a rhombus. The slope of MH is 0 and the slope of HT is 4. Since the slopes are not negative 3 reciprocals, the sides are not perpendicular and do not form rights angles. Since adjacent sides are not perpendicular, quadrilateral MATH is not a square. REF: 011138ge 9 ANS: m AB = 10 3 7 2 = 7 5, m = 4 ( 3) CD 9 4 = 7 5, m = 3 ( 3) AD 2 4 = 6 2 = 3, m = 10 4 BC 7 9 = 6 = 3 (Definition of 2 slope). AB CD, AD BC (Parallel lines have equal slope). Quadrilateral ABCD is a parallelogram (Definition of parallelogram). d AD = (2 4) 2 + (3 ( 3)) 2 = 40, d AB = (7 2) 2 + (10 3) 2 = 74 (Definition of distance). AD is not congruent to AB (Congruent lines have equal distance). ABCD is not a rhombus (A rhombus has four equal sides). REF: 061031b 4

10 ANS: AB CD and AD CB because their slopes are equal. ABCD is a parallelogram because opposite side are parallel. AB BC. ABCD is not a rhombus because all sides are not equal. AB BC because their slopes are not opposite reciprocals. ABCD is not a rectangle because ABC is not a right angle. REF: 081038ge 11 ANS: M 4 + 0 2, 6 1 2 = M 2, 5 2 m = 6 1 4 0 = 7 4 m = 4 7 y 2.5 = 4 (x 2) The diagonals, MT and AH, of 7 rhombus MATH are perpendicular bisectors of each other. REF: fall1411geo 12 ANS: m TS = 10 6 = 5 3 m SR = 3 5 Since the slopes of TS and SR are opposite reciprocals, they are perpendicular and form a right angle. RST is a right triangle because S is a right angle. P(0,9) m RP = 10 6 = 5 3 m = 3 PT 5 Since the slopes of all four adjacent sides (TS and SR, SR and RP, PT and TS, RP and PT ) are opposite reciprocals, they are perpendicular and form right angles. Quadrilateral RSTP is a rectangle because it has four right angles. REF: 061536geo 5

13 ANS: Both pairs of opposite sides of a parallelogram are parallel. Parallel lines have the same slope. The slope of side BC is 3. For side AD to have a slope of 3, the coordinates of point D must be (1,3). m AB = 2 0 5 0 = 2 5 m CD = 5 3 6 1 = 2 5 m AD = 3 0 1 0 = 3 m BC = 5 2 6 5 = 3 REF: 080032a 14 ANS: m AB = 6 + 2, 2 + 8 2 2 = D(2,3) m = 2 + 6 BC 2, 8 + 2 = E(4,3) F(0, 2). To prove that ADEF is a 2 parallelogram, show that both pairs of opposite sides of the parallelogram are parallel by showing the opposite sides have the same slope: m AD = 3 2 2 6 = 5 AF DE because all horizontal lines have the same slope. ADEF 4 m FE = 3 2 4 0 = 5 4 is not a rhombus because not all sides are congruent. AD = 5 2 + 4 2 = 41 AF = 6 REF: 081138ge 6

15 ANS: 7 + 3 M, 4 + 6 2 2 = M( 5,5) N 3 + 3, 6 + 0 2 2 = N(0,3) P 3 + 1 2, 0 + 8 2 = P(2, 4) Q 7 + 1, 4 + 8 2 2 = Q( 3, 2). m MN = 5 3 5 0 = 2 5 m PQ = 4 2 2 3 = 2 5 m NA = 3 4 0 2 = 7 2 m QM = 2 5 3 5 = 7 2. Since both opposite sides have equal slopes and are parallel, MNPQ is a parallelogram. MN = ( 5 0) 2 + (5 3) 2 = 29. MN is not congruent to NP, so MNPQ NA = (0 2) 2 + (3 4) 2 = 53 is not a rhombus since not all sides are congruent. REF: 081338ge 16 ANS:. To prove that ABCD is a trapezoid, show that one pair of opposite sides of the figure is parallel by showing they have the same slope and that the other pair of opposite sides is not parallel by showing they do not have the same slope: m AB = 9 6 7 1 = 3 6 = 1 2 REF: 080134b m CD = 6 1 13 3 = 5 10 = 1 2 m AD = 6 1 1 3 = 5 2 m BC = 9 6 7 13 = 3 6 = 1 2 7

17 ANS:. To prove that KATE is a trapezoid, show that one pair of opposite sides of the figure is parallel by showing they have the same slope and that the other pair of opposite sides is not parallel by showing they do not have the same slope: m AK = 7 5 4 1 = 2 3 m EK = 1 5 1 1 = undefined m ET = 3 ( 1) 7 1 = 4 6 = 2 m 3 AT = 7 3 4 7 = 4 3 To prove that a trapezoid is not an isosceles trapezoid, show that the opposite sides that are not parallel are also not congruent using the distance formula: d EK = (1 1) 2 + (5 ( 1)) 2 = 6 REF: 010333b 18 ANS: d AT = (4 7) 2 + (7 3) 2 = 5. To prove that JKLM is a trapezoid, show that one pair of opposite sides of the figure is parallel by showing they have the same slope and that the other pair of opposite sides is not parallel by showing they do not have the same slope: m JK = 4 ( 2) 13 1 = 1 2 m JM = 2 4 1 ( 2) = 2 m LM = 8 4 6 ( 2) = 1 2 m KL = 4 8 13 6 = 4 7 To prove that a trapezoid is not an isosceles trapezoid, show that the opposite sides that are not parallel are also not congruent using the distance formula: d JM = (1 ( 2)) 2 + ( 2 4) 2 = 45 REF: 080434b d KL = (13 6) 2 + (4 8) 2 = 65 8

19 ANS:. To prove that TRAP is a trapezoid, show that one pair of opposite sides of the figure is parallel by showing they have the same slope and that the other pair of opposite sides is not parallel by showing they do not have the same slope: m TR = 1 4 1 3 = 3 4 m TP = 1 ( 4) 1 ( 1) = undefined m PA = 4 2 1 7 = 3 4 m RA = 4 2 3 7 = 1 2 To prove that a trapezoid is not an isosceles trapezoid, show that the opposite sides that are not parallel are also not congruent using the distance formula: d TP = ( 1 ( 1)) 2 + (1 ( 4)) 2 = 5 d RA = (3 7) 2 + (4 2) 2 = 20 = 2 5 REF: 080933b 20 ANS: PAT is an isosceles triangle because sides AP and AT are congruent ( 3 2 + 11 2 = 7 2 + 9 2 = 130). R(2,9). Quadrilateral PART is a parallelogram because the opposite sides are parallel (m AR = 4 6 = 2 3 ; m PT = 4 6 = 2 3 ; m PA = 11 3 ; m RT = 11 3 ) REF: 011835geo 9

21 ANS: To prove that ABCD is a trapezoid, show that one pair of opposite sides of the figure is parallel by showing they have the same slope and that the other pair of opposite sides is not parallel by showing they do not have the same slope: m AB = 0 0 a a = 0 2a = 0 m CD = c c b b = 0 2b = 0 m AD = c 0 b ( a) = m BC = c 0 b a = c b a c b + a If AD and BC are parallel, then: c b + a = c b a c(b a) = c( b + a) b a = b + a 2a = 2b a = b But the facts of the problem indicate a b, so AD and BC are not parallel. To prove that a trapezoid is an isosceles trapezoid, show that the opposite sides that are not parallel are congruent using the distance formula: d BC = (b a) 2 + (c 0) 2 d AD = ( b ( a)) 2 + (c 0) 2 = b 2 2ab + a 2 + c 2 = a 2 + b 2 2ab + c 2 = (a b) 2 + c 2 = a 2 2ab + b 2 + c 2 = a 2 + b 2 2ab + c 2 REF: 080534b 10