I forgot about the 'other' angle. First the formula to calculate an internal
angle from three known side lengths -

A=ACOS((b^2+c^2-a^2)/(2*b*c))*180/PI()

or as you want internal Angle-B
B=ACOS((a^2+c^2-a^2)/(2*a*c))*180/PI()

=ACOS((35^2+14.8913950730962^2-30^2)/(2*35*14.8913950730962))*180/PI()

= 58.36437249

Deduct your original 20, elevation of lineA from the horizontal
=38.3643724911045

or depending on direction
= 141.635627508895

Regards,
Peter T



"Peter T" <peter_t@discussions wrote in message
...
OK I follow now.

The internal angle between lines a & b is 45-20=25. This angle is opposite
c
and is thus Angle-C

Referring to the formula I posted previously

c = SQRT(a^2 + b^2 - 2*a*b*COS((180-A-B)*PI()/180))

change (180-A-B) to 25 and include the known side lengths a & b

= SQRT(35^2+30^2-2*35*30*COS(25*PI()/180))

= 14.8913950730962

Somehow Dana managed to obtain an extra 2dp of precision beyond the
capabilities of my Excel <g

Regards,
Peter T

"Cathy" wrote in message
...
Sorry if I am confusing things by not explaining 100%

This is very usefull to me as my head is hurting going through Trig
websites
trying to remember everything again.

Okay let me try again from scratch

# A B C
1 Side Direction Length
2 Line1 20 35
3 Line2 45 30
4 Line3 ? ?

Three lines form a triangle. Lets call it Triangle ABC with these
letters
on
each of the corners
(it is not a right Triangle)
Line1 = a = AB
Line2 = b = BC
Line3 = c = CA

Line1 starts at position 0.0
Line1 is angled at 20 degrees from 0 (0 being horizontal)
Line1 is 35 meters long

Line2 starts at position 0.0 also
Line2 is angled at 45 degrees from 0
Line2 is 30 meters long

The difference in angle between Line1 and Line2 is therefore 25 degrees

Line3 completes the Triangle
Need to calculate angle from 0
Need to calculate length

Therefore using Daves Example the angle of side1 would be 25

If you had:
# A B C
1 Angle Length
2 Side1 25 35
3 Side2 ? 30
4 Side3 ? ?

And therefore I have to calculate three values
If formulas for these three can be provided, then I will be very happy.

Hope this makes a little more sense now. (Wish I could draw it as I see
it
in text)

TIA
C