help please

arc XY = 170         arc VW = 110

arc VX + arc WY = 360 - ( 170+110 ) = 80

angle U = ( arc WY - arc VX ) /2 

30 = ( 70 - 10 ) / 2 

arc WY = 70º 

Querty,

Thanks for doing your reask properly and giving the address.

But please, next time, include the address in a proper link.

Dragon,

Thanks for answering but please answer on the original next time and just leave a note on the new ask to say that is what you have done. 

Thanks for asking Qwerty.

Click on the chain link in the ribbon. It is on the bottom left.

And copy your link in.  You can copy it once for the display and once for the link.

Experiment and you will work it out very quickly.