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How to do this junior high school math problem? Help me analyze it! ! ! ! If you are the one! ! ! ! ! ! ! ! ! ! ! ! ! ! !
Solution: according to the meaning of the question, establish a rectangular coordinate system with A as the origin and AB as the east (that is, the abscissa).

It's BN⊥AM, in N, BF⊥AB, in F.

∴∠mab=30&； ordm，∠FBA = 90 & amp； ordm，∠FBM = 15 & amp； ordm,∴∠abm= 105&； ordm,∴∠amb=45&； ordm

∴∠∵bn⊥am bnm = 90 &； Ordm∴δbnm is an isosceles right triangle.

The fishing boat sailed due east at point A at a speed of 28 knots and arrived at point B half an hour later.

∴ AB = 28× 1/2 = 14 nautical mile,

sinNAB = sin30 & ampordm=bn/ab= 1/2,∴bn=ab sin 30 & amp； Ordm= 14/2 = 7 nautical miles.

In the isosceles right angle Δ δBNM, sinBMN=BN/BM/bm, and ∠ bmn = 45 & ordm; The root number 2 of sin 45& = 2.

∴bm=bn/sin45&； Ordm= 7 times the root number 2.

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