# Math Help - angle calculation

1. ## angle calculation

Hi,

I have to calculate theta in the picture. anyone help me.

Thanks.

2. Originally Posted by kumar
Hi,

I have to calculate theta in the picture. anyone help me.

Thanks.
(180 - acute angle) degrees.

3. Originally Posted by kumar
Hi,

I have to calculate theta in the picture. anyone help me.

Thanks.
I think that you should say more information abaout the picture, because i dont know if that fugure is a rectangle o for example, if the line horizontal is middle point... etc

4. Hi
Thanks for ur reply. ie. rectangle only and that horizondal line is in mid point only. for explanation only I drawn that lines.

5. Originally Posted by kumar
Hi
Thanks for ur reply. ie. rectangle only and that horizondal line is in mid point only. for explanation only I drawn that lines.
ok, as your problem havent numbers, theta only can find in function of the other angles, as the picture show, we say that:

$
\begin{gathered}
\sphericalangle CAB = \alpha \hfill \\
\sphericalangle CBA = \beta \hfill \\
\sphericalangle CBD = \theta \hfill \\
\hfill \\
\alpha + \beta + 90 = 180 \Leftrightarrow \alpha + \beta = 90 \hfill \\
\end{gathered}
$

now

$
\beta + \theta = 180 \Leftrightarrow \boxed{\theta = 180 - \beta }
$

but remember that

$
\begin{gathered}
\alpha + \beta = 90 \Leftrightarrow \beta = 90 - \alpha \hfill \\
\hfill \\
\therefore \theta = 180 - \beta \Leftrightarrow \theta = 180 - \left( {90 - \alpha } \right) \hfill \\
\boxed{\theta = 90 + \alpha } \hfill \\
\end{gathered}
$

I hope that you understand it

if you question continue, only post it

P.D: sorry for my bad english

6. Thanks Nacho