Look at the following pic, Mellie

Angle ABC can be found thusly :
sin CAB/ 26 = sin ABC / 24
And sin CAB = sin90 = 1
So
Sin ABC = 24/26
arcsin (24/26) = ABC
And the altitude AX drawn from A to to side BC will be one leg ot the right triangle AXB........so this altitude will be shorter than the altitude drawn from B to side AC, since this altitude is the hypotenuse of triangle AXB. And AX will clearly be shorter than the remaining altitude drawn from C to side AB.
And we can find AX thusly
AX / sinABC = AB / sin AXB
AX / sin[arcsin(24/26)] = AB / sin AXB
But AXB = 90 so the sine of this angle = 1 and AB = 10.....so we have
AX = 10 * sin[arcsin(24/26)] = 120/13 units = about 9.23 units
And this is the shortest altitude
