(i) A quadrilateral is a parallelogram, if mid points of diagonals AC and BD are same. (ii) A parallelogram is not a rectangle, if diagonals AC ≠ BD. (iii) A parallelogram may be a rhombus if AB = BC. (iv) If in a parallelogram diagonals are equal, then it is rectangle. In a rectangle if the sides AB = BC, then the rectangle is a square. For parallelogram with vertices A(2, –2), B(7, 3), C(11, –1), D(6, –6). mid point of AC = mid point of BD \Rightarrow\left(\frac{2+11}{2}, \frac{-2-1}{2}\right)=\left(\frac{7+6}{2}, \frac{3-6}{2}\right)\\ \Rightarrow\left(\frac{13}{2}, \frac{-3}{2}\right)=\left(\frac{13}{2}, \frac{-3}{2}\right), \text { which is true. } Hence, ABCD is a parallelogram. How, we will check whether AC = BD or AC2 = BD2 \Rightarrow(11-2)^{2}+(-1+2)^{2}=(6-7)^{2}+(-6-3)^{2}\\ \Rightarrow(9)^{2}+(1)^{2}=(-1)^{2}+(-9)^{2}\\ \Rightarrow 81+1=1+81\\ \Rightarrow 82=82, \text { which is true. } As the diagonals are equal so it is a rectangle or square. Now, we will check whether adjacent sides AB = BC \text { or } \mathrm{AB}^{2}=\mathrm{BC}^{2}\\ \Rightarrow(7-2)^{2}+(3+2)^{2}=(11-7)^{2}+(-1-3)^{2}\\ \Rightarrow 5^{2}+5^{2}=(4)^{2}+(-4)^{2}\\ \Rightarrow 25+25=16+16\\ \Rightarrow 50 \neq 32, \text { which is false. } So, ABCD is not a square. Hence ABCD is a rectangle.
Solution: Given, the points are A(2, -2) B(7, 3) C(11, -1) and D(6, -6) We have to find the type of a quadrilateral formed by the given points. The distance between two points P (x₁ , y₁) and Q (x₂ , y₂) is √[(x₂ - x₁)² + (y₂ - y₁)²] Distance between A(2, -2) and B(7, 3) = √[(7 - 2)² + (3 - (-2))²] = √[(5)² + (5)²] = √(25 + 25) = 5√2 Distance between B(7, 3) and C(11, -1) = √[(11 - 7)² + (-1 - 3)²] = √[(4)² + (-4)²] = √(16 + 16) = 4√2 Distance between C(11, -1) and D(6, -6) = √[(6 - 11)² + (-6 - (-1))²] = √[(-5)² + (-5)²] = √(25 + 25) = 5√2 Distance between A(2, -2) and D(6, -6) = √[(6 - 2)² + (-6 - (-2))²] = √[(4)² + (-4)²] = √(16 + 16) = 4√2 Distance between A(2, -2) and C(11, -1) = √[(11 - 2)² + (-1 - (-2))²] = √[(9)² + (1)²] = √(81 + 1) = √82 Distance between B(7, 3) and D(6, -6) = √[(6 - 7)² + (-6 - 3)²] = √[(-1)² + (-9)²] = √(81 + 1) = √82 We observe that AB = CD and BC = AD. Also, AC = BD The opposite sides of the quadrilateral are equal. The diagonals of the quadrilateral are equal. Therefore, the given points represent a rectangle. ✦ Try This: Name the type of quadrilateral formed, if any, by the following points, and give reasons for your answer:(-1, -2), (1, 0), (-1, 2), (-3, 0) ☛ Also Check: NCERT Solutions for Class 10 Maths Chapter 7 NCERT Exemplar Class 10 Maths Exercise 7.3 Problem 3 Summary: The type of a quadrilateral formed by the points A (2, –2), B (7, 3), C (11, –1) and D (6, –6) taken in that order is a rectangle as the opposite sides and diagonals are equal ☛ Related Questions: Open in App Suggest Corrections The points are A(2, –2), B(7, 3), C(11, –1) and D(6, –6) Using distance formula, d = `sqrt((x_2 - x_1)^2 + (y_2 - y_1)^2)` AB = `sqrt((7 - 2)^2 + (3 + 2)^2` = `sqrt((5)^2 + (5)^2` = `sqrt(25 + 25)` = `sqrt(50)` = 5`sqrt(2)` BC = `sqrt((11 - 7)^2 + (-1 - 3)^2` = `sqrt((4)^2 + (-4)^2` = `sqrt(16 + 16)` = `sqrt(32)` = `4sqrt(2)` CD = `sqrt((6 - 11)^2 + (-6 + 1)^2` = `sqrt((-5)^2 + (-5)^2` = `sqrt(25 + 25)` = `sqrt(50)` = `5sqrt(2)` DA = `sqrt((2 - 6)^2 + (-2 + 6)^2` = `sqrt((-4)^2 + (4)^2` = `sqrt(16 + 16)` = `sqrt(32)` = `4sqrt(2)` Finding diagonals AC and BD, we get, AC = `sqrt((11 - 2)^2 + (-1 + 2)^2` = `sqrt((9)^2 + (1)^2` = `sqrt(81 + 1)` = `sqrt(82)` And BD = `sqrt((6 - 7)^2 + (-6 - 3)^2` = `sqrt((-1)^2 + (-9)^2` = `sqrt(1 + 81)` = `sqrt(82)` The Quadrilateral formed is rectangle. |