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About Basic Geometry — Class 6 Olympiad

Identify and classify geometric shapes, understand points, lines, angles, and solve visual reasoning problems. This topic is part of the Olympiad Class 6 mathematics syllabus (chapter: Module 8). On this page you can practice 47 questions across three difficulty levels — 20 easy, 10 medium, and 17 hard — each with a visual step-by-step solution, plus a timed 27-question mastery test with a live leaderboard. Worked examples and sample questions from the topic are below.

Basic Geometry — solved examples for Class 6 Olympiad

Example 1easy

How many distinct line segments can be drawn by connecting any two points from a set of 5 points, no three of which are collinear?
  1. A)A) 5
  2. B)B) 10
  3. C)C) 15
  4. D)D) 20

Step-by-step solution

  1. To form a line segment, we need to choose 2 points out of the given 5 points.
  2. The number of ways to choose 2 points from 5 is given by the combination formula nC2 = n × (n-1) / 2.
  3. Substituting n = 5, we get 5 × (5-1) / 2 = 5 × 4 / 2 = 20 / 2 = 10.

Answer: B) 10

Example 2medium

In the given figure, three distinct straight lines intersect at a single point O. If two of the angles formed around O are 45° and 65°, what is the measure of the third angle that is adjacent to both of these angles along a straight line?
  1. A)60°
  2. B)70°
  3. C)75°
  4. D)80°

Step-by-step solution

  1. When three angles are adjacent to each other on a straight line, their sum is 180°.
  2. Given two angles are 45° and 65°.
  3. Let the third angle be x. So, 45° + 65° + x = 180°.
  4. 110° + x = 180°, which means x = 180° - 110° = 70°.

Answer: 70°

Example 3hard

Given 7 distinct points in a plane, such that exactly 4 of them are collinear, and no other three points are collinear. How many distinct straight lines can be drawn by joining any two of these points?
  1. A)15
  2. B)16
  3. C)18
  4. D)21

Step-by-step solution

  1. If no three points were collinear, the number of distinct lines would be given by the combination formula C(n, 2) = n × (n-1) / 2.
  2. For 7 points, this would be C(7, 2) = 7 × 6 / 2 = 21 lines.
  3. However, 4 points are collinear. These 4 points would form C(4, 2) = 4 × 3 / 2 = 6 lines if they were not collinear, but they only form 1 single line.
  4. So, we subtract the extra lines formed by the collinear points and add back the single line they actually form: 21 - 6 + 1 = 16 distinct lines.

Answer: 16

Practice questions on Basic Geometry

  1. Q1.easy

    An angle measures 125°. Which of the following statements is TRUE about this angle?
    1. A)A) It is an acute angle.
    2. B)B) It is a right angle.
    3. C)C) It is an obtuse angle.
    4. D)D) It is a reflex angle.
    Show answer

    Answer: C) It is an obtuse angle.

    Hint: Recall the definitions of different angle types based on their measure relative to 90°, 180°, and 360°.

  2. Q2.easy

    I am a closed figure with 4 sides, but all my sides are not necessarily equal. My opposite sides are parallel, and all my angles are right angles. What shape am I?
    1. A)A) Square
    2. B)B) Rhombus
    3. C)C) Rectangle
    4. D)D) Trapezium
    Show answer

    Answer: C) Rectangle

    Hint: Carefully consider each property given and eliminate shapes that do not fit all criteria.

  3. Q3.easy

    Which of the following English capital letters has exactly two lines of symmetry?
    1. A)A) A
    2. B)B) H
    3. C)C) E
    4. D)D) Z
    Show answer

    Answer: B) H

    Hint: Sketch each letter and draw all possible lines that divide it into two identical halves.

  4. Q4.medium

    How many distinct triangles can be identified in a regular six-pointed star (also known as a hexagram or Star of David) formed by two overlapping equilateral triangles?
    1. A)10
    2. B)12
    3. C)14
    4. D)16
    Show answer

    Answer: 10

    Hint: Systematically count triangles by their size and orientation. Start with the smallest, then progressively larger ones.

  5. Q5.medium

    A quadrilateral has all its four sides equal in length. It also has exactly two obtuse angles and exactly two acute angles. What kind of quadrilateral is it?
    1. A)Square
    2. B)Rhombus
    3. C)Rectangle
    4. D)Trapezium
    Show answer

    Answer: Rhombus

    Hint: Consider the definitions and properties of quadrilaterals based on side lengths and angle types. What shape has all equal sides but not necessarily 90° angles?

  6. Q6.medium

    In a given circle, a chord is drawn that passes through the center. Another chord is drawn that does NOT pass through the center. Which of the following statements is always true?
    1. A)All chords are equal length.
    2. B)The chord not passing through the center is always longer.
    3. C)The chord passing through the center is the longest chord.
    4. D)Chords cannot be straight lines.
    Show answer

    Answer: The chord passing through the center is the longest chord.

    Hint: Recall the special name given to a chord that passes through the center of a circle and its property regarding length.

  7. Q7.hard

    How many triangles are there in the given figure, which is a regular pentagon with all its diagonals drawn?
    1. A)20
    2. B)25
    3. C)30
    4. D)35
    Show answer

    Answer: 35

    Hint: Systematically count triangles by their size or by the number of vertices they share with the main pentagon. Don't forget the smallest ones and the largest ones.

  8. Q8.hard

    A rectangular sheet of paper is folded in half, then folded in half again in the same direction. A circular hole is punched through the exact middle of the final folded paper. How many holes will be visible when the paper is completely unfolded?
    1. A)1
    2. B)2
    3. C)4
    4. D)8
    Show answer

    Answer: 4

    Hint: Visualize the layers of paper created by each fold. Each layer will have a hole.

  9. Q9.hard

    What is the maximum number of distinct regions into which a plane can be divided by 4 distinct straight lines?
    1. A)8
    2. B)10
    3. C)11
    4. D)12
    Show answer

    Answer: 11

    Hint: Draw the lines one by one and count the new regions formed. Each new line should intersect all previous lines at distinct points to maximize regions.

These are 9 of the 47 questions available for Basic Geometry. Start practicing above to unlock visual solutions, AI coaching, and the topic leaderboard — completely free.