From your trigonometric functions, you can say that :
, so
And also, of course :
, so
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.
Answer:
My progress:
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.
tan ratio:
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
So just put it together...
that's how i did it?