For any equation,

assume solution of a form, 
Which leads to,

Simplify to,

Then find solutions,

For non repeated real root y, we have a form of,

Following up,
For two non repeated complex roots
where,

and,
the general solution has a form of,

Or in this case,

Now we just refine and get,

Hope this helps.
r3t40
The given figure can be drawn as,
From the figure,


Since angle of incidence will be equal to angle of reflection,
Therefore, the height of cactus is 6 m.
Xy+24=x22 that is the answer hope it helps