# Determine if the points (1, 5), (2, 3) and (- 2, - 11) are collinear

**Solution:**

The distance between the two points can be measured using the distance formula which is given by: Distance Formula = √ [(x₂ -^{ }x₁)^{2} + (y₂ - y₁)^{2}]

Let the points (1, 5), (2, 3), and (- 2, - 11) be represented as A, B, and C.

For A, B, and C to be collinear, they must lie on the same line.

Hence, we will have to check if AB + BC = AC or BC + AC = AB or AB + AC = BC.

We know that the distance between any two points is given by,

Distance Formula = √ [(x₂_{ - }x₁)^{2} + (y₂ - y₁)^{2}] ....(1)

To find AB, the Distance between the Points A (1, 5) and B (2, 3), let x₁ = 1, y₁ = 5, x₂ = 2, y₂ = 3

∴ AB = √(2 - 1)² + (3 - 5)² (By Substituting in (1))

= √5

To find BC Distance between Points B (2, 3) and C (- 2, - 11), let x₁ = 2, y₁ = 3, x₂ = - 2, y₂ = - 11

Therefore, BC = √(-2 - 2)² + (-11 - 3)²

= √(- 4)² + (-14)² (By Substituting in the Equation (1))

= √16 + 196

= √212

To find AC Distance between Points A (1, 5) and C (-2, -11), let x₁ = 1, y₁ = 5, x₂ = -2, y₂ = -11

Therefore, CA = √(-2 - 1)² + (-11 - 5)²

= √(-3)² + (-16)² (By Substituting in the Equation (1))

= √9 + 256

= √265

AB = √5, BC = √212, CA = √265

Since AB + AC ≠ BC and BC + AC ≠ AB and AB + BC ≠ AC, therefore, the points (1, 5), (2, 3), and (- 2, - 11) are not collinear.

**☛ Check: **NCERT Solutions Class 10 Maths Chapter 7

**Video Solution:**

## Determine if the points (1, 5), (2, 3) and (- 2, - 11) are collinear

NCERT Class 10 Maths Solutions Chapter 7 Exercise 7.1 Question 3

**Summary:**

The points (1, 5), (2, 3) and (- 2, - 11) are not collinear.

**☛ Related Questions:**

- Check whether (5, - 2), (6, 4) and (7, - 2) are the vertices of an isosceles triangle.
- In a classroom, 4 friends are seated at the points A, B, C and D as shown in Fig. 7.8. Champa and Chameli walk into the class and after observing for a few minutes Champa asks Chameli, “Don’t you think ABCD is a square?” Chameli disagrees. Using distance formula, find which of them is correct.
- Name the type of quadrilateral formed, if any, by the following points, and give reasons for your answer:(i) (- 1, - 2), (1, 0), (- 1, 2), (- 3, 0) (ii) (- 3, 5), (3, 1), (0, 3), (- 1, - 4) (iii) (4, 5), (7, 6), (4, 3), (1, 2)
- Find the point on the x-axis which is equidistant from (2, - 5) and (- 2, 9).

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