The magnitude of the resultant of two vectors of magnitude 3 units and 4 units is 5 units. What is the angle between two vectors?

When can a theory be modified if a new type of technology allows for new observations that raise new questions? a-immediately, while the questions about the theory are being asked b-after new hypotheses related to the theory are tested in experiments c-only after the new observations disprove all parts of the theory d-while scientists begin to think about how the theory could improve