If these two shapes are similar, what is the measure of the missing length v?

(Smaller triangle length: 24, 4 cm)
(Bigger triangle length: 42 cm, v)

First, we need to determine the ratio of corresponding sides in the similar triangles.

Ratio of corresponding sides = 42/24 = 1.75

Now we can use this ratio to find the missing length:
v = 4 * 1.75
v = 7 cm

Therefore, the missing length v is 7 cm.