Navaid Fixes RNAV

Here you need to know what information each navaidnavaid —Navigation Aid is providing you with.

• If it is a bearing (NDBNDB —Non-Directional Beacon or VORVOR —VHF Omnidirectional Range or VDFVDF —VHFVHFVHF —Very High Frequency —Very High Frequency direction finding) then that is an angle expressed in mathematical terms as the angle "theta" from an axis (in this case, north.)
• If the beacon is giving you a distance (like DMEDME —Distance Measuring Equipment) then that is expressed in mathematical terms as the distance "rho" from the origin.

To get a fix, you need two position lines, be they distances or bearings. VDFVDF —VHFVHFVHF —Very High Frequency —Very High Frequency direction finding can be received automatically by any two stations listening out on frequency, but for the remainder you need two separate beacons. Combining the terms for the two beacons (eg VORVOR —VHF Omnidirectional Range = "theta", DMEDME —Distance Measuring Equipment = "rho", so VORVOR —VHF Omnidirectional Range/DMEDME —Distance Measuring Equipment = rho/theta) will give the answer.