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What is the length of the common rafter if the rise is 1.2m and the span is 3.0m? Use: AB=(Squared)AC2 + CB2 Type in your answer to 3 decimal places Read More
7y, 2m agoPosted 7 years, 2 months ago
What is the length of the common rafter if the rise is 1.2m and the span is 3.0m?

Use: AB=(Squared)AC2 + CB2

7y, 2m agoPosted 7 years, 2 months ago
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#1
I thought i was untill i saw this
#2
shosie
I thought i was untill i saw this

Ha, Same ;-)
#3
shosie;8523198
I thought i was untill i saw this

lol my thoughts exactly
#4
Pythags theorum

AB=(square route of(1.2^2 + 1.5^2))

AB = (square route of (1.44 + 2.25)

AB= (square route of (3.69))

AB = 1.9209372712298546059464653023865

AB = 1.921 (3dp)
#5
You got a diagram? And I think you need to re-type the formula, it's too ambiguous as it is....
#6
think it needs the pythagorus theroy. thats about as far as i can get.
1 Like #7
you get the 1.5 from half the span, ie the peak of the roof is going to be at the half way point of the span. Therefore you have a triangle with height 1.2, width 1.5, and the pependictular line petween them is AB, ie the rafter.
#8
ThePasty
you get the 1.5 from half the span, ie the peak of the roof is going to be at the half way point of the span. Therefore you have a triangle with height 1.2, width 1.5, and the pependictular line petween them is AB, ie the rafter.

Are You A Roofer Buy Any Chance? Or A Maths Teacher? You A Genius, Thanks, I Left Some Rep :thumbsup::thumbsup:
#9
AahBisto
Are You A Roofer Buy Any Chance? Or A Maths Teacher? You A Genius, Thanks, I Left Some Rep :thumbsup::thumbsup:

Sadly neither but did degree and love maths. :thumbsup:
#10
ThePasty
Sadly neither but did degree and love maths. :thumbsup:

Okay, Well Thanks Again, I Will Send You A Message If I Have Any More Questions If Thats Okay? :)
#11
AahBisto
Okay, Well Thanks Again, I Will Send You A Message If I Have Any More Questions If Thats Okay? :)

yeah ok
#12
If the span is 3m across and the height is 1.2m you will need to split the 3m in half to get a smaller triangle so as to obtain the sloping length.
The sloping lengths are therefore (1.5x1.5) + (1.2x1.2) and then squre root this answer.
so 1.5x1.5 = 2.25
1.2x1.2 = 1.44
so sloping beam is square root of 2.25+1.44 = 1.921m.

Hope this helps.
#13
briggsa30
If the span is 3m across and the height is 1.2m you will need to split the 3m in half to get a smaller triangle so as to obtain the sloping length.
The sloping lengths are therefore (1.5x1.5) + (1.2x1.2) and then squre root this answer.
so 1.5x1.5 = 2.25
1.2x1.2 = 1.44
so sloping beam is square root of 2.25+1.44 = 1.921m.

Hope this helps.

I Did Sort Of Understand That, Thanks :)
Repped+