Selina Concise Class 6 Math Chapter 21 Fundamental Concepts Exercise 21B Solution
EXERCISE 21B
(1) State, which of t following is a plane closed figure:
Ans: (i), (iii), (vi) and (viii)
(2) Fill in the blanks:
(i) Triangle is a three sided plane closed figure.
(ii) A square is a plane closed figure which is not bounded by any curved line.
(iii) A rectangle is a four sided plane closed figure.
(iv) A rectangle has opposite sides parallel and adjacent sides perpendicular to each other.
(v) The sides of a square are equal to each other and each angle is 90o.
(vi) For a line segment, a line making angle of 90o with it, is called perpendicular to it.
(vii) For a line segment, a line bisecting it and making angle of 90o with it, is called perpendicular bisector of the line segment.
(viii) Infinite.
(ix) Only one.
(x) A perpendicular to a line segment will be its perpendicular bisector if it passes through the mid-point of the given line segment.
(3) State, which of the lines/line-segments are perpendicular to the line PQ:
Ans: CD and MN
(4) Which of the following figures shows two mutually perpendicular line:
Ans: (i) and (iii)
(5) For each figure given below name the line segment that is perpendicular bisector of the other:
(i) AB of CD
(ii) AB of MN
(iii) PQ of RS and Rs of PQ; PQ and RS are perpendicular bisectors of each other.
(iv) None
(v) None
(6) Class room, text book and note-book.
(7) Using the given figure, answer the following:
(i) l ∕∕ m and p ∕∕ q.
(ii) p and l, p and m, q and l, q and m.
(iii) No
(iv) Yes
(9) (i) 18
(ii) 24
(10) Give two examples from your surroundings for each of the following:
(i) Edges of our text book through any corner of it
(ii) Opposite edges of our book
(iii) Adjacent edges at each end of our book
(11) State true or false, if false, give the correct statement:
(i) False; only one line passes through three collinear points
(ii) False; No lines passes through all the three non-collinear points
(iii) True
(iv) True
(v) True
(vi) True
(vii) True
(viii) True
(ix) True.