Angle measures and segment lengths

[Nori]

I have to find y

I tried solving for x first though, so:
a*b=x*x

28*9 = x*x
252=x^2
x=15.87 or √(252)

Now I'm stuck as to how to use this to solve for y

 

[lev888]

Can you look up the relevant formulas?

 

[Dr.Peterson]

You appear to have the right formula, ab = x^2, but not the right definition for the variables in it.

See the formula here: https://en.wikipedia.org/wiki/Tangent-secant_theorem