## ML Aggarwal Class 8 Solutions for ICSE Maths Chapter 16 Symmetry Reflection and Rotation Objective Type Questions

**Mental Maths**

Question 1.

Fill in the blanks:

(i) A figure has ………….. symmetry if it is its own image under a reflection.

(ii) A kite has ………….. line(s) of symmetry.

(iii) A parallelogram has ………….. line(s) of symmetry.

(iv) The centre of rotation of an equilateral triangle is the point of intersection of its …………..

(v) The centre of rotation of a rhombus is the point …………..

(vi) A regular polygon of n-sides has ………….. number of lines of symmetry.

(vii) Angle of rotational symmetry in an equilateral triangle is …………..

(viii) Angle of rotational symmetry in a regular pentagon is …………..

(ix) If after a rotation of 45° about a fixed point the figure looks exactly the same, then the order of rotational symmetry is …………..

Solution:

(i) A figure has line symmetry if it is its own image under a reflection.

(ii) A kite has one line(s) of symmetry.

(iii) A parallelogram has none line(s) of symmetry.

(iv) The centre of rotation of an equilateral triangle is the

point of intersection of its angle bisectors/altitudes/median.

(v) The centre of rotation of a rhombus is the

point of intersection of its diagonals.

(vi) A regular polygon of n-sides has n number of lines of symmetry.

(vii) Angle of rotational symmetry in an equilateral triangle is 120°.

(viii) Angle of rotational symmetry in a regular pentagon is 72°.

(ix) If after a rotation of 45° about a fixed point the figure looks

exactly the same, then the order of rotational symmetry is 8.

Question 2.

State whether the following statements are true (T) or false (F):

(i) A parallelogram has diagonals as its lines of symmetry.

(ii) A regular triangle has three lines of symmetry, one point of symmetry and has rotational symmetry of order 3.

(iiii) A, regular quadrilateral has four lines of symmetry, one point of symmetry and has . rotational symmetry of order 4.

(iv) A parallelogram has no rotational symmetry.

(v) A regular pentagon has one point of symmetry.

(vi) The letter Z has one line of symmetry.

Solution:

(i) A parallelogram has diagonals as its lines of symmetry. False

Correct:

A parallelogram has no line of symmetry.

(ii) A regular triangle has three lines of symmetry,

one point of symmetry and has rotational symmetry of order 3. False

Correct:

A rectangle has 2 lines of symmetry,

one point of symmetry and rotational symmetry of order 2.

(iii) A regular quadrilateral has four lines of symmetry,

one point of symmetry and has rotational symmetry of order 4. True

(iv) A parallelogram has no rotational symmetry. False

Correct:

A parallelogram has rotational symmetry of order 2.

(v) A regular pentagon has one point of symmetry. False

Correct:

A regular pentagon has no point of symmetry.

(vi) The letter Z has one line of symmetry. False

Correct:

The letter Z has no line of symmetry.

**Multiple Choice Questions**

**Choose the correct answer from the given four options (3 to 6):**

Question 3.

The number of lines of symmetry which a quadrilateral cannot have

(a) 1

(b) 2

(c) 3

(d) 4

Solution:

Number of lines of symmetry in

a quadrilateral cannot have three. (c)

Question 4.

A possible angle of rotation of a figure having rotational symmetry of order greater than or equal to 2 is

(a) 36°

(b) 144°

(c) 150°

(d) 360°

Solution:

Two possible angles of rotation of a figure having rotational

symmetry of order greater than or equal to 2 is 36°. (a)

Question 5.

The figure which does not have both line and rotational symmetry is

Solution:

The figure which does not have both lines

and rotational symmetry is a figure given in (c).

Question 6.

The letter which has both line and rotational symmetry is

Solution:

The letter which has both lines and rotational symmetry is .