Find Unit Vector and Angel

Suppose that you are climbing a hill whose shape is given by https://webwork.uncc.edu/webwork2_fi...c3ed134d01.png, and that you are at the point (90, 50, 300).

In which direction (unit vector) should you proceed initially in order to reach the top of the hill fastest?

https://webwork.uncc.edu/webwork2_fi...91631cfb61.png,https://webwork.uncc.edu/webwork2_fi...a27ce889b1.png

If you climb in that direction, at what angle above the horizontal will you be climbing initially (radian measure)?

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(Headbang)help me understand and solve this one.