# Important Questions for CBSE Class 6 Maths Chapter 5 - Understanding Elementary Shapes

## CBSE Class 6 Maths Important Questions Chapter 5 - Understanding Elementary Shapes - Free PDF Download

**Ch – 5 ****Understanding Elementary Shapes**

- How many right angles do you make if you start facing south and turn clockwise to west?
- 1
- 2
- 3
- 4

- Find the number of right angles turned through by the hour hand of a clock when it goes from 3 to 6.
- 4
- 2
- 1
- 3

- What fraction of a clockwise revolution does the hour hand of a clock turn through, when it goes from 12 to 3?
- $\frac{1}{3}$
- 1
- $\frac{1}{2}$
- $\frac{1}{4}$

- What is the angle name for half a revolution?
- Right angle
- Straight angle
- Complete angle
- Reflex angle

- How do we write “$\overrightarrow{\mathrm{P}\mathrm{Q}}$ is perpendicular to $\overrightarrow{\mathrm{R}\mathrm{S}}$” symbolically?
- $\overleftrightarrow{PQ}//\overleftrightarrow{RS}$
- $\overleftrightarrow{PQ}\ne \overleftrightarrow{RS}$
- $\overleftrightarrow{PQ}\mathrm{\perp}\overleftrightarrow{RS}$
- $\overleftrightarrow{PQ}=\overleftrightarrow{RS}$

**Match the following 3D shape and its edges.**Column A Column B 1. Cube (a) 6 2. Square pyramid (b) 12 3. Triangular prism (c) 8 4. Triangular pyramid (d) 9 **Fill up the following:**- Measure of a complete angle is ____________
^{o}. - The triangle in which ____________ sides are equal is called isosceles triangle.
- Each of its angles rectangle measures ____________
^{o}. - A cube has ____________ vertices.

- Measure of a complete angle is ____________
**State true or false:**- Sum of any two sides of a triangle is greater than the third side.
- An equilateral triangle is also considered as an isosceles triangle
- A polygon is regular if its all sides are equal.
- Opposite faces of a cuboid are equal in size.

- How many faces a tetrahedron have?
- What is the angle name for half a revolution?
- Draw a hexagon and write its sides and diagonals?
- If B is the mid point of $\overline{AC}$ and C is the point of $\overline{\mathrm{B}\mathrm{D}}$ . where A, B, C, D lie on a straight line, say why AB = CD?
- Draw a rough sketch of a regular octagon. Draw a rectangle by joining exactly four of the vertices of the octagon.
- Measure the angles given below, using the Protractor and write down the measure.

- All equilateral triangle are isosceles, but all isosceles triangle are not equilateral. Justify the statement.

**Answer**

- 1

Explanation: The four main direction north, east, south, west. Each of them are at 90^{o}clockwise, i.e. we have to move 90^{o}to move north to east, another 90^{o}from east to south like that.

So South to west we have to move only one 90^{o}. so answer is 1

- 1
- 1

Explanation: Hour hand move 360^{o}from 12 to 12 . So it moves 3 hr from 3 to 6 . The factor of 3 to 12 $=3/12=1/4$

Right angle = 90^{o}, factor of 90^{o}with 360^{o }$=90/360=1/4.$

So Hour hand will turn one right angle to cross 3 to 6

- 1
- (d) $\frac{1}{4}$ Explanation: In clock hour hand moves 12 hr from 12 o’ clock to 12 o’ clock. Fro12 to it 3 it is 3 hr , so fraction of 3 hr from 12 hr $=3/12=1/4$. Or, the hour hand moves360
^{o}form 12 to 12, from 12 to 3 it moves 90^{o}, so fraction of 90^{o}from 360^{o}$=90/360=1/4$

- (d) $\frac{1}{4}$ Explanation: In clock hour hand moves 12 hr from 12 o’ clock to 12 o’ clock. Fro12 to it 3 it is 3 hr , so fraction of 3 hr from 12 hr $=3/12=1/4$. Or, the hour hand moves360
- Straight angle

Explanation: One revolution = 360^{o }

Half revolution $x=\frac{-b\pm \sqrt{{b}^{2}-4ac}}{2a}$ 180^{o}

180^{o}is called straight angle

- Straight angle
- $\overleftrightarrow{PQ}\mathrm{\perp}\overleftrightarrow{RS}$ Explanation: $\overleftrightarrow{PQ}\mathrm{\perp}\overleftrightarrow{RS}$

- – b
- – c
- – d
- – a

- 360
- two
- 90
- 8

- True
- False; in isosceles triangle only two sides are equal.
- False; For a polygon to be regular, all sides as well as all angles have to be equal.
- True

- In geometry, a tetrahedron is a polyhedron composed of four triangular faces, three of which meet at each corner or vertex.
- Straight Angle (180°)
- Hexagon

Sides of hexagon: AB, BC, CD, DE, EF and FA.

Diagonals of hexagon: AC, AD, AE, BD, BE, BF, CE, CF, and DF

$\because $ B is the mid-point of $\overline{AC}$

∴ AB = BC …(1)

$\because $C is the mid-point of $\overline{BD}$

∴ BC = CD …(2)

In view of (1) and (2), we get

AB = CD.- 45°
- 125°
- 90°
- ∠1 = 40°, ∠2 = 125° and ∠3 = 95°.

- An isosceles triangle is any triangle with 2 sides that are equal in length. So every equilateral triangle is a special case of an isosceles triangle since not just 2 sides are equal, but all 3 are. But every isosceles triangle is not equilateral, because you can have 2 sides of equal length and a third side that is either longer or shorter than those 2 sides. For example, if the triangle is a right-angle triangle and the two sides that meet to make the right angle are the same length, then the 3rd side would be longer than those two.