
LinkBack  Thread Tools  Display Modes 
12162010, 06:57 AM  #1 (permalink) 
LIFETIME MEMBER
Join Date: Nov 2008
Location: NH
Posts: 3,529

Calling all Mathmeticians..Need some help with angles
Can anyone confirm this? I'm trying to find the angles of stairs for my drop in. It's 10 feet tall, with 12 ladder stairs. It's been awhile since i've had to use geometry.

Sponsored Links  
Advertisement


12162010, 07:35 AM  #4 (permalink)  
Senior Member
Join Date: Oct 2010
Location: Seattle
Posts: 99

Quote:
I assume that you want the angles from predetermined/built lengths. So, using cos then taking the bottom right angle first, cos(x) = adjacent/hypotenuse > cos(x) = 6.6/12 > using inverse cosine, the bottom angle should be 56.63 degrees. Then, taking the top left angle, using cos(x) = adj/hypotenuse > cos(x) = 10/12 > inverse cosine, the top angle is 33,56 degrees, 33.56+56.53 = 90.09, so the angles match with the lengths Last edited by rainboarding; 12162010 at 07:42 AM. Reason: effed my math up. oops. 

12162010, 07:43 AM  #5 (permalink) 
Drunk with power...er beer.

A quick application of pythagoras says that the sides at 10, 6.6 and 12 are almost exactly correct. I don't have a calc with trig functions in front of me, so I can't confirm the actual angles.
__________________
I told my kids, "Someday, you'll have kids of your own." One of them said, "So will you."  Rodney Dangerfield. 
12162010, 08:16 AM  #7 (permalink) 
Veteran Member
Join Date: Oct 2009
Location: Mt. Bachelor
Posts: 1,539

Recall from trigonometry (not geometry) the mnemonic "SOH CAH TOA."
sin theta = opposite/hypotenuse sin theta = 10/12 sin theta = 0.83 calculator.com  Online Scientific Calculator Checks out. 
12162010, 04:07 PM  #10 (permalink) 
Senior Member
Join Date: Nov 2008
Location: massachusetts
Posts: 108

Mathematically that would work out but practically I think you would want 90+45+45 so you have a better down ramp also if you increase your drop angle the length on the bottom must increase hopefully that made sense and for your third side the Pythagorean theorem A^2+b^2=c^2 should help
Last edited by bostonboarder; 12162010 at 04:09 PM. 
Thread Tools  
Display Modes  

