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Angles Quiz - CBSE Class 6 Mathematics

Free practice quiz: Angles (CBSE Class 6 Mathematics). 16 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This CBSE Class 6 Mathematics practice quiz has 16 multiple-choice questions on Angles, and 16 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

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Angles and their types

  • An angle is formed by two rays that share a common endpoint called the vertex.
  • A right angle is a quarter turn. Acute is smaller than a right angle. Obtuse is between right and straight.
  • A straight angle is a half turn. A complete angle is one full turn around a point.
Right angle
\[\text{right angle} = \tfrac{1}{4}\text{ turn}\]
Straight angle
\[\text{straight angle} = 2 \times \text{right angle} = \tfrac{1}{2}\text{ turn}\]
Complete angle
\[\text{complete angle} = 4 \times \text{right angle} = 1\text{ turn}\]

Common mistake: Judging an angle by the length of its arms. The size depends only on how wide the arms open.

Pairs of angles

  • Supplementary angles add up to a straight angle. Complementary angles add up to a right angle.
  • Angles on a straight line form a straight angle. Vertically opposite angles are always equal.
Supplementary
\[a + b = \text{straight angle}\]
Complementary
\[a + b = \text{right angle}\]
Vertically opposite angles
\[\angle 1 = \angle 3\]

Common mistake: Mixing up complementary and supplementary angles. Complementary makes a right angle. Supplementary makes a straight angle.

Angles of a triangle

  • The three angles of any triangle add up to a straight angle.
  • Acute triangle: all angles acute. Right triangle: one right angle. Obtuse triangle: one obtuse angle.
  • If the sides satisfy a^2 + b^2 = c^2, the triangle is right-angled.
Angle sum
\[a + b + c = \text{straight angle}\]
Missing angle
\[c = \text{straight angle} - (a + b)\]
Right triangle test (c longest)
\[a^2 + b^2 = c^2\]

Common mistake: Classifying a triangle using only the two given angles. Always find the third angle first, then decide.

Interior angles of a polygon

  • Diagonals from one vertex split a polygon with n sides into (n - 2) triangles.
  • Each triangle adds one straight angle to the total.
Sum of interior angles
\[S = (n - 2) \times \text{straight angle}\]

Common mistake: Multiplying the number of sides n by a straight angle. You must use (n - 2), the number of triangles.

Parallel lines and a transversal

  • A transversal is a line that cuts two or more lines.
  • When the lines are parallel, alternate interior angles and corresponding angles are equal.
  • Interior angles on the same side add up to a straight angle.
Alternate interior angles
\[\angle x = \angle y\]
Co-interior angles
\[\angle p + \angle q = \text{straight angle}\]

Common mistake: Assuming alternate angles are equal when the lines are not parallel. The rule works only for parallel lines.

Exam tips

Beta: made with AI and checked by a second AI. A teacher has not reviewed it yet.

Sample questions

  1. What is an angle?

    Show answer

    Answer: B. A measure of rotation

    An angle is defined as a measure of rotation between two rays that share a common endpoint. The correct answer is 'A measure of rotation'.

  2. If one angle in a triangle is 50 degrees and another is 60 degrees, what is the third angle?

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    Answer: A. 70 degrees

    In a triangle, the sum of angles is always 180 degrees. Therefore, the third angle is 180 - 50 - 60 = 70 degrees.

  3. If two angles are supplementary, what is their total measure?

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    Answer: B. 180 degrees

    Supplementary angles are those that add up to 180 degrees.

  4. If the measure of an angle is tripled and equals 180 degrees, what is the original measure of the angle?

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    Answer: B. 60 degrees

    Let the original angle be x. Then 3x = 180 implies x = 60 degrees.

  5. If a polygon has 8 sides, what is the sum of its interior angles?

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    Answer: C. 1080 degrees

    The sum of interior angles of a polygon can be found using the formula (n-2) * 180, where n is the number of sides. Therefore, for an 8-sided polygon, the sum is (8-2) * 180 = 1080 degrees.

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More questions in this quiz

Answers and explanations are in the full quiz.

  1. Which of the following is an acute angle?
  2. What do we call an angle that is exactly 90 degrees?
  3. What type of angle is greater than 90 degrees but less than 180 degrees?
  4. In a straight line, what is the total measure of angles formed?
  5. How many degrees are there in a complete circle?
  6. A right triangle has one angle measuring 90 degrees and another measuring 45 degrees. What is the measure of the third angle?
  7. In a triangle, if one angle is 70 degrees and the other is 40 degrees, what is the type of the triangle based on its angles?
  8. If two angles are vertical, what is true about their measures?
  9. A triangle has sides of length 3 cm, 4 cm, and 5 cm. What type of triangle is it based on its angles?
  10. If two parallel lines are cut by a transversal, what are the alternate interior angles?
  11. What is the relationship between the angles of a triangle and the angles formed by its medians?

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