Question 888434
see the picture below.


check the comments below the picture.


<img src = "http://theo.x10hosting.com/2014/072702.jpg" alt="$$$" </>


the picture shows the diagram of the situation as i understand it.


step 1 establishes that BC is equal to 140 * tan(30).


step 2 establishes that BD = 140 * tan(60).


step 3 goes through the calculations to find CD which is equal to BD minus BC.


you could have just used your calculator to find 140 * (tan(60) - tan(30)).


the extra calculations in step 3 were because I used the exact value of tan(30) and tan(60), the resolution of which required more calculations than using your calculator directly.


if you use your calculator, make sure it's in degree mode as you will get a very screwy answer if you have it in radian mode, since the angles are expressed in degrees.