Answer:
31 cm
Step-by-step explanation:
Theorem: If two chords are equidistant from the center of a circle, then they and their arcs are congruent, and conversely.
Using this theorem,
JK = LM.
So,
3x+19 = 6x+7
Solve this equation:
3x-6x = 7-19
-3x = -12
3x = 12
x = 4
If x = 4 cm, then
JK = 3·4+19 = 12+19 = 31 cm
