Q1 of 10 Page 68

Answer the following:

i. How many dimensions a solid has?


ii. How many books are there in Euclid’s Elements?


iii. Write the number of faces of a cube and cuboid.


iv. What is sum of interior angles of a triangle?


v. Write three un-defined terms of geometry.

i. A solid has 3 dimensions, namely length, breadth and height.


ii. Euclid of Alexandria in Egypt wrote 13 books called ‘The Elements’.


iii. A cube is also a cuboid having 6 faces. Hence, both cube and cuboid have 6 faces.


iv. By equivalent of fifth postulate, we know that the sum of angle of a triangle is a constant and is equal to two right angles.


∴ Sum of interior angles of a triangle = 180°


v. In geometry, a point, a line and a plane are the un-defined terms.


More from this chapter

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2

State whether the following statements are true or false? Also give reasons for your answers.

a) Only one line can pass through a given point.


b) All right angles are equal.


c) Circles with same radii are equal.


d) A finite line can be extended on its both sides endlessly to get a straight line.



e) From the figure, AB > AC

 3

In the figure given below, show that length AH > AB + BC + CD.

 4

If a point Q lies between two points P and R such that PQ = QR, prove that PQ = 1/2 PR.

 5

Draw an equilateral triangle whose sides are 5.2 cm each.