Subject Re: Solve Oblique Triangle
From Norman Snowden <duluth@msn.com>
Date Mon, 08 Apr 2019 13:50:04 -0400
Newsgroups dbase.getting-started


Thanks Mervyn, you solved the problem!


Mervyn Bick Wrote:

> On 2019-04-08 6:19 AM, Norman Snowden wrote:
> > I realize this is not a normal subject and a Post should not be necessary. However, any comment would be appreciated. Thanks, Norman Snowden
> >
> > Solve Oblique Triangle. Clockwise start at A to C to B
> >
> > Without an actual picture please follow this description:
> >
> >  From A, extend a line due north for a distance of 20 feet to Point C
> >  From C, extend a line at North 85.24 degrees West for an unknown distance toward point B
> >  From A, extend a line at North 45 degrees West an unknown distance toward B to intercept the line from C to B.
> >
> > The angle at A is 45 degrees and the angle at point C is 94.76 degrees.
> > The angle at point B is 180 – (45 + 9 4.76) = 40.23 degrees
> >
> > The distance B to C is a  which is opposite A
> > The distance A to B is c which is opposite C
> > The distance A to C is b which is opposite A and is known as 20 feet.
> >
> >  From the Law of Sines with b = 20
> > 20/sinB = c/sinC = a/sinA
> >
> > c = (20 *sinB)/sin C       a = (20 *sinB)/sinA
> > c = 12.96 feet  and  a = 18.27 feet
>
> Here's the problem.
>
>    c = (20/sinB)*sinC
>    a = (20/sinB)*sinA
>
>
> >  
> > These values are wrong.  When the triangle is drawn to scale  c  = +- 35 feet and a = +- 25 feet.
> >
> > This could be solved using Slope Intercept Equations but that should not be necessary.
> >
> > The triangle meets the Law of Sines requirements and the solution should be simple.
>
> The SIN() function in dBASE requires its argument to be in radians.  The
> dBASE function DTOR() will convert degrees to radians.
>
> *****
> b = 20
> aA = 45
> aC = 180 - 85.24
> aB = 180 - (aA + aC)
>
> c = b/sin(dtor(aB))*sin(dtor(aC))
> a  = b/sin(dtor(aB))*sin(dtor(aA))
>
> ?'aA = '+aA
> ?'aB = '+aB
> ?'aC = '+aC
> ?
> ? 'a = '+a
> ? 'b = '+b
> ? 'c = '+c
> ********
>
> This gives the following output
>
> aA = 45
> aB = 40.24
> aC = 94.76
>
> a = 21.89
> b = 20
> c = 30.85
>
>
> Mervyn.
>
>
>
>