Oh darn, he did it for you before I could post this!
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Instead of doing your problem for you, I'll do one that is exactly like
yours in every way, step by step.
The problem I will do is this one:
the altitude of a right triangle divides the hypotenuse into two segments of 9cm and 4cm length. Find the area of triangle
Sketch the triangle:
Find the length of the altitude:
Cross multiply:
Now do your problem exactly the same way, step by step.
Edwin