# problem solving basic tan equation!

• Aug 20th 2011, 03:58 AM
glxej
problem solving basic tan equation!
Hi all,

I have an equation which I cannot solve. I have the values and the answer, but I am unable to recreate it myself. Any help would be appreciated as I need to apply this to my own numbers....

To calculate an angle (A) = tanH/(D-d)

Where H=1.5, D= 2.5 and d=0.5. The answer I have been given is 56 degrees.

I have tried every combination of things and am getting nowhere in recreating the answer, can someone tell me what I am doing wrong?

E
• Aug 20th 2011, 04:10 AM
Siron
Re: problem solving basic tan equation!
Imo the question is not clear.
Is the equation:
$A=\frac{\tan(H)}{D-d}$
?
If you know $H,D,d$ then you can enter them in the given equation.
• Aug 20th 2011, 04:33 AM
glxej
Re: problem solving basic tan equation!
I don't know, the equation posted is exactly how it is written in the article I got it from. However, as I said, I have tried different combinations and still am not getting the answer (including from your suggestion).

Perhaps I need a step by step - calculator-type instruction because I must be missing something somewhere for it not to work...
• Aug 20th 2011, 04:36 AM
e^(i*pi)
Re: problem solving basic tan equation!
Code:

tan ( 1 . 5) / (2 . 5 - 0 . 5 )
Some calculators demand the argument of the tan first so in that case do 1.5 tan

That being said I get an answer of A = 0.0131 (3sf)

What are your units? As it stands tan(H) is dimensionless so what are D and d
• Aug 20th 2011, 04:44 AM
Siron
Re: problem solving basic tan equation!
I suppose the given information $H,D,d$ are in radians ...
I would say:
$A=\tan\left(\frac{1,5}{2}\right) \Leftrightarrow A\approx 0,9316 \mbox{rad}\approx 53,37$°
• Aug 20th 2011, 05:23 AM
glxej
Re: problem solving basic tan equation!
The dimensions of H, D and d are all in km.