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Coordinate Geometry Formulas

July 17, 2023 | by Bloom Code Studio

The list of all coordinate geometry formulas for classes 9, 10, and 11 is provided here to help the students. To recall, coordinate geometry is the study of geometry using the coordinate points. In coordinate geometry, the position of a point can be easily defined using coordinates.

Coordinate Geometry Formulas List for Classes 9, 10 and 11

Coordinate geometry is an integral topic in classes 9, 10 and 11. All the important coordinate geometry formulas for class 9, class 10 and class 11 are given below.

All Formulas of Coordinate Geometry
General Form of a LineAx + By + C = 0
Slope Intercept Form of a Liney = mx + c
Point-Slope Formy − y1= m(x − x1)
The slope of a Line Using Coordinatesm = Δy/Δx = (y− y1)/(x− x1)
The slope of a Line Using General Equationm = −(A/B)
Intercept-Intercept Formx/a + y/b = 1
Distance Formula|P1P2| = √[(x− x1)+ (y− y1)2]
For Parallel Lines,m= m2
For Perpendicular Lines,m1m2 = -1
Midpoint FormulaM (x, y) = [½(x+ x2), ½(y+ y2)]
Angle Formulatan θ = [(m– m2)/ 1 + m1m2]
Area of a Triangle Formula½ |x1(y2−y3)+x2(y3–y1)+x3(y1–y2)|
Distance from a Point to a Lined = [|Ax+ By+ C| / √(A+ B2)]
Section Formula (Internal division)P(x, y) = [(m1x2 + m2x1)/(m1 + m2), (m1y2 + m2y1)/(m1 + m2)]
Section Formula (External division)P(x, y) = [(m1x2 – m2x1)/(m1 – m2), (m1y2 – m2y1)/(m1 – m2)]

Solved Examples

Example 1: 

What is the slope of the line joining the points P(-2, 3) and Q(2, 7)?

Solution:

Let the given points be:

P(-2, 3) = (x1, y1)

Q(2, 7) = (x2, y2)

Solpe of the line PQ = (y2 – y1)/(x2 – x1)

= (7 – 3)/ [2 – (-2)]

= 4/4

= 1

Example 2:

If the distance between the points A(2, –2) and B(–1, x) is 5, find the value of x.

Solution:

Let the given points be:

A(2, -2) = (x1, y1)

B(-1, x) = (x2, y2)

Distance between A and B = √[(x2 – x1)2 + (y2 – y1)2]

√[(-1 – 2)2 + (x + 2)2] = 5 [given distance is 5]

Squaring on both sides, we get;

(3)2 + (x + 2)2 = 25

(x + 2)2 = 25 – 9

(x + 2)2 = 16

x + 2 = ± 4

When x + 2 = 4, x = 2

When x + 2 = -4, x = -6

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