Question 381584
Draw a picture.
.
.

{{{drawing(300,300,-10,10,-10,10,line(-9,-9,2,2),line(2,2,2,-9),line(2,-9,-9,-9),locate(-4,-9,30),locate(2.5,-4,H),locate(-5,-1,2H+2))}}}
.
.
.

Use the Pythagorean theorem,
{{{(2H+2)^2=30^2+H^2}}}
Solve for {{{H}}}.