Q2 of 50 Page 10

Make the following number sequences from the sequence of equilateral triangles, squares, regular pentagons and so on, of regular polygons.

Number of sides – 3,4,5…


Sum of interior angles –


Sum of exterior angles –


One interior angle –


One exterior angle –

For the following sequences, let


a = First term of sequence


d = common difference if the sequence is an AP


a) Number of sides – 3,4,5,6,7…. And so on is an Arithmetic Progression.


Where a = 3 and d = 1


b) Sum of interior angles of a regular polygon with n sides = (n-2)×180


Putting n = 3, 4, 5, 6… and so on


The required sequence is 180,360,540,720… and so on.


An AP with a = 180 and d = 180


c) Sum of exterior angles of any closed polygon is 360


Hence the sequence is 360,360,360… and so on i.e. AP with a = 360 and d = 0


d) One Interior angle = (Sum of all interior angles)/(No. of sides)


=


Putting n = 3, 4, 5… and so on…


The sequence is 60, 90, 108, 120… and so on. Here, the sequence is not an AP


e) One exterior angle =


( no. of exterior angles = no. of sides)


=


Putting n = 3, 4, 5… and so on


The sequence is 120, 90, 72, 60… and so on which is clearly not an AP.


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