Re: Crosswind application(s)
ToPocHi
The crosswind component varies as a function of the sine of the wind angle (the difference between your track and the wind direction). As the sine of 90 is 1 you have full crosswind in your scenario; if the wind was 30 degrees off track you would have a crosswind component of sine 30=0.5. As your approach speed is 70kts it would seem that you are flying a light training aircraft which will probably have a Demonstrated max crosswind limit of about 17kts.
The point your instructor is making, I would imagine, is that although it would be possible to track the centreline all the way down final in this case, it would be unlikely that there would be enough rudder authority to correct the drift before touchdown. It would also be illegal to attempt to land with the crosswind compenent outside the demonstrated safe limits for that aircraft. This is an airmanship test and the answer to your instructor should be "The crosswind is outside the limits for the aircraft and I need to ask for another runway or divert to an airport that has a more suitable runway." Of course, this scenario should be dealt with at the pre-flight planning stage as 25 kt winds are usually predicted in the Tafs.