From your trigonometric functions, you can say that :
And also, of course :
Now, you know that , so ( )
How did you find your result ? It might be interesting to see your reasoning
A truss is used to hold up a heavy sign on a building, as shown.
The truss is attached to the building along side AB, which measures 2.4m. Determine an exact expression for the length CD.
I found out that side a is approximately 1m. What the heck is going on with that expression though?
edit: Bacterius beat me to it.. oh well
Well I got my exact value and the answer is same as the one you provided. Here's how I did it:
To find CD you need to find BC and BD. Then subtract BC from BD.
You don't even need a calculator for this..
Set up the BD triangle and ignore the diagonal line through the middle.
The angle is 45 and we need to find the adjacent.
In this equation
We know that tan45 is 1 so...
Now do the BC triangle..
The angle is 60 and you need to find adjacent.
Use tan again:
We should know that tan60 is
So just put it together...
that's how i did it?