Use the triangle below to find cos∠v.

First you need to remember that cos is adjacent over hypotenuse. 

the H here is side VU
the A is 6( youre being asked about angle V)
The O is going to be 15.

cosV=6/H

I think in this instance you need to figure out the length of H to find angle V. 
pygorthean  thery: a^2+b^2=c^2
c is always hypotenuse. a and b can be either opposide or adjeacnt, however you want. 

15^2+6^2=c^2
225+36=c^2
261=c^2
square root of 261=c(hypotenuse)

so now we go back to the cos equation
cosV=6/square root of 261
the angle  pf cosV is 68.28 degrees

I am not sure what else youre looking for. 

Ibelieve the answer would be 7, 13, 23