1. ## Show that v=90-x

I need help with this task. Can somone tell whats obvious and give a couple of clues.

2. Originally Posted by kevin3000
I need help with this task. Can somone tell whats obvious and give a couple of clues.

I've modified your sketch a little bit:

1. $|\theta| = 180^\circ - 2x$

2. $|\theta| = 2v$

Substitute $\theta$ in 2. by 1. and solve for v.