Tag: maths

Questions Related to maths

State true or false: 

Is it possible to have a regular polygon whose each exterior angle is 40% of a right angle.

  1. True

  2. False


Correct Option: A
Explanation:

Given, regular polygon whose each exterior angle is 40% of a right angle = $ 90^o \times \dfrac{40}{100} = 36^o $
Sum of all exterior angle of any polygon is $ 360^o $
Now,
$ 36^o \times$  number    of   angles  = $ 360^o $
The number  of  angles =$ 10 $
Any polygon have equal number of angles and sides.
Therefore the number of side of the polygon is 10.
Since the number of sides is an integer, therefore their exist a polygon whose each exterior angle is 40% of a right angle. 

State true or false.
Is it possible to have a regular polygon whose each exterior angle is $32^{\circ}$

  1. True

  2. False


Correct Option: B
Explanation:

Given, a regular polygon whose each exterior angle is $32^o $
Each exterior angle of a regular polygon = $ \dfrac {360^o}{n} $, where n = number of side
Now,
$ \dfrac {360^o}{n} = 32^o $
$=> n = \dfrac{45}{4} $
Since, n should be an integer, so it is not possible a regular polygon whose each exterior angle is $32^o $

State true or false: 
Is it possible to have a regular polygon whose each exterior angle is $80^o$
80∘

  1. True

  2. False


Correct Option: B
Explanation:

Let the number of sides of the polygon is n. (which must be an integer)
If each exterior angle is $ 80^o $, then sum of all exterior angle is $ n \times 80^o $.
And Sum of all exterior angles = $ 180^o $
$=>  n \times 80^o = 180^o $
$=> n = 1.25 $
So, it is not possible to have a regular polygon whose each exterior angle is $ 80^o $

State true or false.
Is it possible to have a regular polygon whose each exterior angle is $20^{\circ}$

  1. True

  2. False


Correct Option: A
Explanation:

Given, a regular polygon whose each exterior angle is $20^o $
Each exterior angle of a regular polygon = $ \dfrac {360^o}{n} $, where n = number of side
Now,
$ \dfrac {360^o}{n} = 20^o $
$=> n = 18 $
Since, n should be an integer, so their exist a regular polygon whose each exterior angle is $20^o $

How many sides does a regular polygon have if the measure of an exterior angle is $24^o$?

  1. $15$

  2. $12$

  3. $14$

  4. $16$


Correct Option: A

Find the measure of exterior angle of a regular polygon of 15 sides

  1. $36^o$

  2. $24^o$

  3. $48^o$

  4. none of the above


Correct Option: B
Explanation:

The sum of the exterior angles of a regular polygon is $360^o$

Number of sides of polygon $=15$
As each of the exterior angles are equal,

Exterior angle $=\dfrac{360^o}{15}=24^o$

Find the measure of exterior angle of a regular polygon of 9 sides

  1. $40^o$

  2. $60^o$

  3. $50^o$

  4. $30^o$


Correct Option: A
Explanation:

Each exterior angle of a regular polygon of 9 sides
$=\dfrac {360^o}{n}$, where $n=9=\left (\dfrac {360^o}{9}\right )^o=40^o$

If the sum of all interior angles of a convex polygon is 1440, then the number of sides of the polygon is

  1. 8

  2. 10

  3. 11

  4. 12


Correct Option: B
Explanation:

If n is the number of sides of the polygon, then $(2n -4)\times 90^o = 1440$
or 2n = 20          or          n = 10

An exterior angle of regular polygon is $\displaystyle 12^{\circ}$ the sum of all the interior angles is

  1. $\displaystyle 4040^{\circ}$

  2. $\displaystyle 5040^{\circ}$

  3. $\displaystyle 6040^{\circ}$

  4. $\displaystyle 7040^{\circ}$


Correct Option: B
Explanation:

Given the exterior angle of regular polygon is 12

We know each  exterior angle of regular polygon=$\dfrac{360}{n}$ where n is the sides of polygon
$\dfrac{360}{n}=12\Rightarrow n=30$
we know that interior angle of  regular polygon=$180(n-2)=180(30-2)=5040^{0}$

The measure of the external angle of a regular hexagon is 

  1. ${\pi/3}$

  2. ${\pi/4}$,

  3. ${\pi/6}$

  4. None


Correct Option: A
Explanation:

$\Rightarrow$ Sum of exterior angles of a regular hexagon $=360^o$

$\Rightarrow$  Number of sides of regular hexagon $=6$
$\Rightarrow$  The measure of the external angle of a regular hexagon $=\dfrac{360^o}{6}=60^o$
In radian $=60^o\times \dfrac{\pi}{180^o}=\dfrac{\pi}{3}$