The shortest side (the one opposite the 30o angle) is 1/2 the hypotenuse.
The shortest side = 7/2 = 3.5
The other side can before using a^2 + b^2 = c^2
c = 7
b = 3.5
a = x
x^2 + 3.5^2 = 7^2
x^2 + 12.25 = 49
x^2 = 36.75
x = sqrt(36.75)
x = 6.062
Check
6.062^2 + 3.5^2 =? 7^2
36.75 + 12.25 = 49
49 = 49 It does check.