Telangana SCERT Class 9 Math Solution Chapter 3 The Elements of Geometry Exercise 3.1

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

Updated: September 18, 2021 — 4:46 pm


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