Q51Written answer
Order of rotational symmetry of the following figure is_________.
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Ans: Octagon possesses eight orders of rotational symmetry.
Order of rotational symmetry is $8$.
NCERT Exemplar · Class 7 · Maths
Chapter 12: Practical Geometry Symmetry and Visualising Solid Shapes
Practice each question, then open the answer or worked solution.
Textbook exercises
124 questionsQ52Written answer
A __________ triangle has no lines of symmetry.
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Ans: In scalene triangle all sides and angles are unequal and so there is no line of symmetry.
A Scalene triangle has no lines of symmetry.
Q53Written answer
Cuboid is a rectangular_________ .
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Ans: Rectangular prism and cuboid refers to the same solid body.
Cuboid is a rectangular prism.
Q54Written answer
A sphere has __________vertex, __________edge and __________curved surface.
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Ans: Sphere is a solid body with zero vertex, zero edge and one curved surface.
A sphere has $0$ vertex, $0$ edge and $1$ curved surface.
Q55Written answer
The following figure is a net of a __________.
→ Circumference of circle = ______.
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Ans: On observing the given figure, it represents a cone.
Therefore It is the net of a cone.
→ Circumference of circle ${\text{ = 2}}\pi r$.
Q56Written answer
The following is a net of a __________.
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Ans: On observing the given figure, it represents a triangular prism.
Therefore it is a net of a triangular prism.
Q57Written answer
Order of rotational symmetry of the following figure is __________.
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Ans: Given figure represents an isosceles triangle.
Isosceles triangle possesses one order of rotational symmetry.
Order of rotational symmetry is one.
Q58Written answer
Identical cubes are stacked in the corner of a room as shown below. The number of cubes that are not visible are _________.
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Ans: There are $20$ such cubes which are not visible.
Identical cubes are stacked in the corner of a room as shown below. The number of cubes that are not visible are $20$.
In Questions from 59 to 92, state whether the statements are True or False.
Q59Written answer
We can draw exactly one triangle whose angles are ${{70}^{\circ}, {30}^{\circ }}$ and ${\mathbf{80^\circ }}$.
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Ans: This is not true exactly as there can be infinite number of triangles with angles ${70}^{\circ} ,{30}^{\circ} $ and ${80}^{\circ} $ with various different combinations of sides.
Therefore, the given statement is False.
Q60Written answer
The distance between the two parallel lines is the same everywhere.
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Ans: The distance between the two parallel lines is always the same everywhere.
Therefore, the given statement is True.