Telangana SCERT Solution Class IX (9) Math Chapter 3 The Elements of Geometry Exercise 3.1
(1.) (i.) How many dimensions a solid has?
Ans. 3
(ii.) How many books are there in Euclid’s Elements ?
Ans. 13
(iii.) Write the number of faces of cube and cuboid.
Ans. Cubes and Cuboids have 6 faces.
(iv.) What is sum of interior angles of a triangle ?
Ans. Sum of interior angle of a triangle is 1800
(v.) Write three un-defined terms of geometry.
Ans. The undefined terms in geometry are point, plane and line.
(2) a) Only one line can pass through a given point.
Ans. False.
b) All right angles are equal.
Ans. True.
c) Circles with same radii are equal.
Ans. True.
d) A line segment can be extended on its both sides endlessly to get a straight line.
Ans. True.
e) Ans. True.
(6.) What is a conjecture ? Give an example for it.
Ans. A conjecture is a statement that is believed to be tree based or observations. A conjecture might not have any formal proof.
For example: If I write a set of even number from 2 to 10 and ask someone to tell me next number he shall say 12.
2, 4, 6, 8, 10, ..
Now this is a conjecture based on observation which is believed to be true but it does not have any proof.
(7.) Mark two points P and Q. Draw a line through P and Q. Now how many lines which are parallel to PQ, can you draw?
(8) In the adjacent figure, a line n falls on lines l and m such that the sum of the interior angles 1 and 2 is less than 180°, then what can you say about lines l and m.
(9.) In the adjacent figure, if ∠1 = ∠3, ∠2 = ∠4 and ∠3 = ∠4, write the relation between ∠1 and ∠2 using an Euclid’s postulate.
(10.) In the adjacent figure, we have BX = 1/2 AB, BY = 1/2 BC and AB = BC. Show that BX = BY
Good
Good but you teacher’s are finding we had wrote from the internet
In the solutions, which are great, you have used the word, “Postulate,” when it should have been “Axiom.” Don’t you think so?