# help with maths question

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#1
http://www.mrarmstrong.net/exampaper...larHigher2.pdf question 9 , ty.
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6 years ago
#2
External angles on a regular shape add up to 360. As y is an external angle, and it's an octagon, you divide 360 by 8 to get 45

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#3
(Original post by thelexisquiche)
External angles on a regular shape add up to 360. As y is an external angle, and it's an octagon, you divide 360 by 8 to get 45

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nop that's not the answer mate.
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6 years ago
#4
Each interior angle is (n-2)*180/n = 135. 135/2 is 67.5, so the angle is 180-67.5 = 112.5
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#5
(Original post by Eux)
What thelexisquiche said- if you want to check by another method, each interior angle is (n-2)*180/n = 135. 180 - 135 is 45- a more complex method but you get the answer nonetheless
ok guys, seriously 45 is not the answer, apprently it's 112.5
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#6
(Original post by missaxo)
why do you hate hannah?
Spoiler:
Show
work out the interior angles of the octagon (n-2) x180/n = 135
so angle BAE would be 135
and then 180-135 = 45 would be the angle PAB

alternatively:
you can work out the exterior angle, we know exterior angles of polygons add up to 360 so 360/8=45
alright, this is getting ridiculous, all of you are getting it wrong. lol
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6 years ago
#7
(Original post by ihatehannah)
ok guys, seriously 45 is not the answer, apprently it's 112.5
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#8
it dosen't even remotely look like a 45 degree angle guys!! Think about it.
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6 years ago
#9
(Original post by ihatehannah)
alright, this is getting ridiculous, all of you are getting it wrong. lol
how do you know we're getting it wrong? why ask if you're so confident that's the wrong answer?
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#10
(Original post by Eux)
Each interior angle is (n-2)*180/n = 135. 135/2 is 67.5, so the angle is 180-67.5 = 112.5
ok ty that makes sense.
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#11
(Original post by missaxo)
how do you know we're getting it wrong? why ask if you're so confident that's the wrong answer?
the angle looks nothing like 45 degrees!!!!
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6 years ago
#12
The first step is to calculate the interior angles of an octagon. You will need a formula for this, which is (where n is the number of sides of the shape).
So, for an octagon, n=8, so So, there are 1080 degrees inside an octagon, which has 8 interior angles, so

So, each interior angle of an octagon is 135 degrees.
The line AE is bisecting (cutting in half) the octagon, so the angle EAB is half of 135, which is 67.5 degrees.
Since PAE is a straight line, there are 180 degrees on that line, so

Think this should have helped. Tell me if some bits don't make sense, or you do not understand.
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6 years ago
#13
Guys! Definitely not 45 degrees
Since it is a regular octagon, each interior angle is 135 degrees - (n-2) x 180 = 1080; 1080/8 = 135
The line passes through points A and E, meaning that it creates a line of symmetry on either side.
Thus, angle BAE is simply 67.5 degrees (135 divided by 2)
Finally, angles on a straight line equate to 180 degrees - which means y=180-67.5 = 112.5 degrees

Soooooooo... THE ANSWER IS 112.5 degress
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6 years ago
#14
I got 112.5. Line of symmetry
Good question!
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6 years ago
#15
angle HAB = (number of sides) - 2 x 180 degrees
8 -2 x 180 degrees = 1080 degrees

only need angle HAB so we do 1080 degrees / 8 = 135 degrees

SO THE MIDPOINT OF HAB IS 67.5 degrees

TO FIND y WE SIMPLY TAKE 62.5 AWAY FROM 180
THIS IS BECAUSE ALL ANGLES IN A TRIANGLE ADD TO 180 DEGREES

THIS GIVES A FINAL ANSWER OF 112.5 ----- just finished my yr 11 maths exams and faced the 2015 ed excel maths paper so trust me on this answer LOL

p.s why are you doing maths work in the holidays :-o
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6 years ago
#16
(Original post by ihatehannah)
nop that's not the answer mate.
It's been a long time since I've done a problem like this sorry ;-:

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