Triangular Whatchamacallum

[Chupu]

The question and possible answers are in the picture below.

http://img81.imageshack.us/img81/7792/screenshot20091015at806k.png

One of my friend says it is 23 km/h North but I beg to differ.

[Feldoh]

What makes you thing it wouldn't be 23 km/h? Your friends answer seems right to me.

Perhaps we can help you if you explain your thought process as to why that answer seems wrong.