In solving for the unknown side x of a triangle with other sides 4 cm and 5 cm and area 6 cm2, a quadratic equation gives the roots x=3 cm and x=12 cm. Which choice correctly identifies the valid value of x?
a) Both 3 cm and 12 cm, since both roots are positive
b) 3 cm, because the three lengths satisfy the triangle inequality
c) 12 cm, because the larger root corresponds to the given area
d) Neither value, because the triangle inequality is not met