OpenEuphoria

2. Re: How to calculate the height of a triangle given the "pitch" and the length of the hypotenuse?

• Posted by cargoan Jul 28, 2013
• 2317 views

b = c * sin(deg2rad(B)) 
a = c * cos(deg2rad(B)) 

4. Re: How to calculate the height of a triangle given the "pitch" and the length of the hypotenuse?

• Posted by DonCole Aug 11, 2013
• 2076 views

-- given: 
c = 122 -- the hypotenuse 
B = 2.23 -- degrees, the "pitch" or "slope" (0.0384941) 
 
-- need to calculate: 
b -- the triangle height/side opposite the hypotenuse 
a -- length triangle base 
 
-- once I have the length of b, I can calculate a using 
-- the Pythagorean theorem. 

b = c * sin(deg2rad(B)) 
a = c * cos(deg2rad(B)) 

Wait a minuet here. This post got me interest in designing a triangle calculator.

Don't you have to have 3 elements to calculate a triangle?

side, side, side
side, angle side
angle, side, angle
angle, angle, angle

given:
c = 122 the hypotenuse
B = 2.23 degrees, the "pitch" or "slope" (0.0384941)

According to cargoan's calculations
b = c * sin(deg2rad(B))
a = c * cos(deg2rad(B))

a=122
b=0

Don Cole

6. Re: How to calculate the height of a triangle given the "pitch" and the length of the hypotenuse?

• Posted by Euman Aug 11, 2013
• 2049 views

if you always come to 180 degrees 'solid' your calculation is correct

8. Re: How to calculate the height of a triangle given the "pitch" and the length of the hypotenuse?

• Posted by K_D_R Aug 15, 2013
• 1965 views

Yes, the triangle described is a right triangle. The trig functions provided by Arthur worked perfectly. The height of the triangle in question represents the amount of "rise" which must be added to one end of a riser wall in a three frequency geodesic dome. The height calculated for b = 4.74714403.

But then I got to thinking. Even though the values for the height of the "rise" of the riser wall and the "run", or length of the riser wall are not chords. They are values which are proportional to the size of the geodesic dome and the reference sphere. Therefore, with simple algebra, x * sphere_radius = 4.74714403, x = 4.74714403/295.8 = 0.0160484923259

A a riser wall for a three frequency geodesic dome with a spherical radius of 295.8cm will need to be 4.7~cm higher on one end. ( pictures and discussions on the webpage domerama.com will help to illustrate what I am referring to )

The ratio accurately predicts the necessary "rise" for a three frequency dome's rise wall when the reference sphere radius is 485.1 cm ( 485.1 * 0.0160484923259 = 7.785123627294 = 7.8cm )

It appears that the architect who drew up the plans for which I have these two datasets rounded the figures down to nearest "mm".

Thanks to everyone for all the help and feedback.

Ken Rhodes