plzz answer the 24th q
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Answers
Answer:
n = 3
Step-by-step explanation:
Given, Smallest angle = a = 52°
Common difference = d = 8°.
Let the polygon has 'n' number of sides.
Given that the angles are in A.P.
Let the angles of the polygon are:
a,a + d, a + 2d...
(i) Sum of n terms:
= (n/2)[2a + (n - 1) * d]
= (n/2)[104 + (n - 1) * 8]
= (n/2)[104 + 8n - 8]
= (n/2)[8n + 96]
= 4n[n + 12]
(ii)
Sum of all the angles of polygon with n sides = (n - 2) * 180
From (i) & (ii), we get
⇒ 4n(n + 12) = (n - 2) * 180
⇒ 4n² + 48n = 180n - 360
⇒ 4n² - 132n + 360 = 0
⇒ n² - 33n + 90 = 0
⇒ n² - 30n - 3n + 90 = 0
⇒ n(n - 30) - 3(n - 30) = 0
⇒ (n - 3)(n - 30) = 0
⇒ n = 3, 30{a + 29d = 52 + 29 * 8 = 284 > 180°.. Not possible }
⇒ n = 3.
Therefore, the value of n is 3.
Hope it helps!
an = 52 + (30 - 1) * 8
= 52 + 240 - 8
= 284
which is not possible
Question
The interior angles of a polygon are in AP.The smallest angle is 52° and the common difference is 8°.Find number it sides in polygon.
ANSWER
Given,
Smallest angle(a) = 52°
Common difference(d) = 8°
Hence the AP formed will be =>
52,60,68,76,84.........
We know,
Sum of interior angles of a polygon=(n-2)180°
Hence,the equation formed is=>
n/2{2a + (n-1)d} = (n-2)180°
=>n/2{2×52 + (n-1)8} = (n-2)180°
=>n/2(104 + 8n -8) = 180n - 360°
=>n/2(96 +8n) = 180n - 360°
=>48n+ 4n^2 = 180n - 360°
=>4n^2 - 132n + 360 = 0
=>4(n^2 - 33n + 90) =0
So,on dividing both sides by 4 we get =>
n^2 - 33n + 90 =0
Since this is a quadratic equation we will have two vales for n.
=>n^2 -30n -3n +90 =0
=>n(n-30) -3(n-30)=0
=>(n-30)(n-3) =0
Hence, either n= 3 or
n = 30(neglected).
So, we get that the number of sides of polygon is 3
thanks