The altitude of a right-angled triangle is 6 cm and the base is increasing at a constant rate of 2cm/s. At what rate it the hypotenuse increasing when its length is 10 cm?

No idea how to do this question. But i did approach it. I tried using similar triangles but it didn't work out. Why?

Let length be y and base be x

At y=10

6/y = x/h

6/10 = x/h

x = 3/5 h

dx/dt = 3/5 dh/dt

thus dh/dt = 10/3 cm/s

The actual answer is 1.6