I'm self taught (still in the beginning ...sad i know)
not sure if it's a mistake by the author i think it's impossible to evaluate JK
since i assume i will always end up having two variables.
i couldn't solve it just thought about it and figured that one of the segments of the hypotenuse should be known so we use the proportion relationship of the segments and the altitude.
and two more things...
1-is there any easier way to draw figures and notate with mathematical symbols rather than playing around with Photoshop.
2- i hope I'm not offending anybody with my English , I'm not aware of my weaknesses on the subject .