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S3 Mathematics

Question post on Wed, 26/01/2022 6:40pm

Please help!

ChiefKiasu · Answer 1 · Post on Wed, 26/01/2022 7:30pm

Let me try.

Sum of interior angles in a polygon of n sides = (n-2) * 180
So, for an octagon, an interior angle = ((8-2)*180) / 8 = 135

(i) If we consider BCDE as a regular polygon,
then sum of its interior angles = 2*180 = 360

So angle EBC = (360 – 135 – 135) / 2 = 45

(ii) angle EBC = 135 – 45 = 90

(iii) angle DCE = (180 – 135) / 2 = 22.5

Mazda12345 · Answer 2 · Post on Sun, 13/02/2022 1:11pm

Mazda12345 Post on Sun, 13/02/2022 1:11pm

Hi, why do u consider BCDE as a regular polygon? Thanks!

ChiefKiasu · Answer 3 · Post on Sun, 13/02/2022 4:16pm

ChiefKiasu Post on Sun, 13/02/2022 4:16pm

Umm… because it is given in the question that the figure is part of an octagon.

Mazda12345 · Answer 4 · Post on Sun, 13/02/2022 6:37pm

I thought that a regular polygon has equal sides, anyway here’s my answer which I find more appropriate

Mazda12345 · Answer 5 · Post on Sun, 13/02/2022 6:37pm

I thought that a regular polygon has equal sides, anyway here’s my answer which I find more appropriate

ChiefKiasu · Answer 6 · Post on Mon, 14/02/2022 9:35am

ChiefKiasu Post on Mon, 14/02/2022 9:35am

Isn’t your answer the same as mine? Well, that’s fine then 🙂