Distance Formula — ICSE Class 9 Maths Important Questions
13 hand-picked ICSE Class 9 Maths important questions for Distance Formula, each with a full model answer — the formats and topics most likely to appear in your board exam.
- 13
- Questions
- 6
- Question types
- 32
- Total marks
- ₹0
- With answers
The ICSE Class 9 Distance Formula gives the distance between A(x_1,y_1) and B(x_2,y_2) as AB=√(x_2-x_1)^2+(y_2-y_1)^2. High-yield questions find lengths of segments, prove figures are isosceles/right-angled/parallelogram, find points equidistant from two given points, and use distance from the origin √x^2+y^2.
About Distance Formula
In the ICSE Class 9 Maths chapter Distance Formula you calculate the straight-line distance between two points A(x_1,y_1) and B(x_2,y_2) on the Cartesian plane using AB=√(x_2-x_1)^2+(y_2-y_1)^2, which follows from Pythagoras' theorem. You apply it to find side lengths, classify triangles and quadrilaterals, test collinearity, and locate points that are equidistant from given points, including distance from the origin √x^2+y^2.
Key concepts & formulas
The distance between A(x_1,y_1) and B(x_2,y_2) is AB=√(x_2-x_1)^2+(y_2-y_1)^2. It is derived from Pythagoras' theorem on the right triangle formed with the axes.
The distance of P(x,y) from the origin O(0,0) is OP=√x^2+y^2, a special case with (x_1,y_1)=(0,0).
Compute side lengths: all sides equal and diagonals equal is a square; all sides equal is a rhombus; opposite sides equal is a parallelogram. A triangle is isosceles if two sides are equal and right-angled if a^2+b^2=c^2.
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Important questions with answers
Try each on paper first, then reveal the model answer to check your method.
| Question type | Count | Marks |
|---|---|---|
| MCQ | 4 | 1 |
| Assertion–Reason | 1 | 1 |
| Very Short | 2 | 2 |
| Short Answer | 3 | 3 |
| Long Answer | 2 | 5 |
| Case-based | 1 | 4 |
Multiple-choice questions (1 mark)
The distance between the points (0,0) and (3,4) is:
- (a)
5
- (b)
7
- (c)
7
- (d)
25
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Answer: (a) 5.
OP=√3^2+4^2=√9+16=√25=5.
The distance between A(2,3) and B(2,8) is:
- (a)
5
- (b)
6
- (c)
√11
- (d)
10
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Answer: (a) 5.
The x-coordinates are equal, so AB=√(2-2)^2+(8-3)^2=√0+25=5.
If the distance between (x,0) and (0,x) is √8 units, then x equals:
- (a)
1
- (b)
2
- (c)
4
- (d)
2
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Answer: (b) 2.
Distance =√(x-0)^2+(0-x)^2=√2x^2=8. So 2x^2=8 x^2=4 x=2 (taking the positive value).
The point on the x-axis equidistant from A(2,-5) and B(-2,9) is:
- (a)
(-7,0)
- (b)
(-3,0)
- (c)
(3,0)
- (d)
(7,0)
Show model answer
Answer: (a) (-7,0).
Let the point be P(x,0). Then PA^2=PB^2:
(x-2)^2+25=(x+2)^2+81.
x^2-4x+4+25=x^2+4x+4+81 -4x+29=4x+85 -8x=56 x=-7. So P(-7,0).
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Practise free with the AI tutor →Assertion–Reason questions (1 mark)
Assertion (A): The triangle with vertices A(0,0), B(4,0) and C(0,3) is right-angled.
Reason (R): In any triangle, if the square of the longest side equals the sum of the squares of the other two sides, the triangle is right-angled.
- (a)
Both A and R are true and R is the correct explanation of A
- (b)
Both A and R are true but R is not the correct explanation of A
- (c)
A is true but R is false
- (d)
A is false but R is true
Show model answer
Answer: (a) AB=4, AC=3, BC=√16+9=5. Since 3^2+4^2=9+16=25=5^2, the triangle is right-angled (at A), and R (the converse of Pythagoras) correctly explains A.
Very short answer questions (2 marks)
Find the distance between the points P(-3,2) and Q(1,-1).
Show model answer
PQ=√(1-(-3))^2+(-1-2)^2=√(4)^2+(-3)^2
=√16+9=√25=5 units.
Find the value of a if the distance of the point (a,3) from the origin is 5 units.
Show model answer
Distance from origin =√a^2+3^2=5.
a^2+9=25
a^2=16
a=±4.
So a=4 or a=-4.
Short answer questions (3 marks)
Show that the points A(1,2), B(5,4) and C(3,8) are the vertices of an isosceles triangle.
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Find each side length.
AB=√(5-1)^2+(4-2)^2=√16+4=√20.
BC=√(3-5)^2+(8-4)^2=√4+16=√20.
CA=√(1-3)^2+(2-8)^2=√4+36=√40.
Since AB=BC=√20, two sides are equal, so ABC is isosceles.
Find the point on the y-axis which is equidistant from the points A(6,5) and B(-4,3).
Show model answer
Let the required point be P(0,y) on the y-axis.
PA=PB PA^2=PB^2:
(0-6)^2+(y-5)^2=(0+4)^2+(y-3)^2.
36+y^2-10y+25=16+y^2-6y+9.
61-10y=25-6y.
61-25=-6y+10y 36=4y y=9.
The point is P(0,9).
Prove that the points A(-2,-1), B(1,0), C(4,3) and D(1,2) are the vertices of a parallelogram.
Show model answer
For a parallelogram, opposite sides must be equal.
AB=√(1+2)^2+(0+1)^2=√9+1=√10.
DC=√(4-1)^2+(3-2)^2=√9+1=√10.
BC=√(4-1)^2+(3-0)^2=√9+9=√18.
AD=√(1+2)^2+(2+1)^2=√9+9=√18.
Since AB=DC=√10 and BC=AD=√18, both pairs of opposite sides are equal, so ABCD is a parallelogram.
Long answer questions (5 marks)
Show that the points A(1,1), B(-1,-1) and C(-3,3) are the vertices of an equilateral triangle. Find the length of each side, leaving the answer in surd form.
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Compute all three sides.
AB=√(-1-1)^2+(-1-1)^2=√4+4=8=22.
BC=√(-3+1)^2+(3+1)^2.
Expand: (-3+1)^2=3-23+1=4-23 and (3+1)^2=3+23+1=4+23.
Sum =8, so BC=8=22.
CA=√(1+3)^2+(1-3)^2=√(4+23)+(4-23)=8=22.
Since AB=BC=CA=22, all three sides are equal, so ABC is equilateral with each side 22 units.
The vertices of a quadrilateral are A(0,0), B(4,3), C(1,7) and D(-3,4), taken in order.
(i) Find the lengths of all four sides.
(ii) Find the lengths of both diagonals.
(iii) Hence prove that ABCD is a square.
Show model answer
(i) Sides.
AB=√(4-0)^2+(3-0)^2=√16+9=√25=5.
BC=√(1-4)^2+(7-3)^2=√9+16=√25=5.
CD=√(-3-1)^2+(4-7)^2=√16+9=√25=5.
DA=√(0+3)^2+(0-4)^2=√9+16=√25=5.
All four sides equal 5 units.
(ii) Diagonals.
AC=√(1-0)^2+(7-0)^2=√1+49=√50.
BD=√(-3-4)^2+(4-3)^2=√49+1=√50.
Both diagonals equal √50=52 units.
(iii) Conclusion. All four sides are equal (5 units), so ABCD is a rhombus. Since the two diagonals are also equal (52), the rhombus is a square. Hence ABCD is a square.
Case-based questions (4 marks)
On a coordinate map (1 unit = 1 km), three mobile towers stand at P(0,0), Q(6,0) and R(3,4). A control room must be built.
(i) Find the distances PQ, QR and RP.
(ii) What type of triangle is PQR?
(iii) Find the distance of R from the origin.
Show model answer
(i)
PQ=√(6-0)^2+(0-0)^2=√36=6 km.
QR=√(3-6)^2+(4-0)^2=√9+16=√25=5 km.
RP=√(3-0)^2+(4-0)^2=√9+16=√25=5 km.
(ii) Since QR=RP=5 km and PQ=6 km, two sides are equal, so PQR is isosceles.
(iii) R from the origin P(0,0): OR=√3^2+4^2=√25=5 km.
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Frequently asked questions
Are these Distance Formula important questions free?
Yes. All 13 ICSE Class 9 Maths important questions for Distance Formula are free, with full model answers and no login required.Do these Distance Formula questions follow the latest ICSE syllabus?
Yes — they are aligned to the CISCE latest syllabus syllabus for ICSE Class 9 Maths, so nothing here is outside the current course.How should I practise the Distance Formula important questions?
Attempt each question on paper first, then reveal the model answer to check your method — not just the final result. Re-do anything you got wrong the same day.What types of questions are covered for Distance Formula?
A full mix — multiple-choice questions, assertion–reason questions, very short answer questions, short answer questions, long answer questions, case-based questions — so every format in the ICSE paper is covered.
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