document.write( "Question 998492: To a person riding a bike with velocity (7 i + 3 j) km/h the wind seems to have velocity (9 i + 10 j) km/h. \r
\n" ); document.write( "\n" ); document.write( "State the true velocity of the wind in i, j vector form.
\n" ); document.write( "velocity (km/h) = \r
\n" ); document.write( "\n" ); document.write( "What is the speed of the wind?
\n" ); document.write( "speed (km/h) = \r
\n" ); document.write( "\n" ); document.write( "Taking i as due East, what is the direction of the wind (in standard bearing notation) to the nearest degree?
\n" ); document.write( "bearing (°) ≈\r
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Algebra.Com's Answer #616417 by ikleyn(52781)\"\" \"About 
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\n" ); document.write( "To a person riding a bike with velocity (7 i + 3 j) km/h the wind seems to have velocity (9 i + 10 j) km/h.
\n" ); document.write( "State the true velocity of the wind in i, j vector form.
\n" ); document.write( "velocity (km/h) =
\n" ); document.write( "What is the speed of the wind?
\n" ); document.write( "speed (km/h) =
\n" ); document.write( "Taking i as due East, what is the direction of the wind (in standard bearing notation) to the nearest degree?
\n" ); document.write( "bearing (°) ≈
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\n" ); document.write( "\n" ); document.write( "To a person riding a bike with velocity  (r*i + s*j)  \"km%2Fh\"  in a  still air  (at no wind)  the wind  seems  to have velocity  (-r*i, -s*j)  \"km%2Fh\".  From here I make a conclusion that \r
\n" ); document.write( "\n" ); document.write( "    - if a person is riding a bike with velocity  (r*i + s*j)  \"km%2Fh\"  relative to the earth surface and \r
\n" ); document.write( "\n" ); document.write( "    - if the wind is  (u*i + v*j)  \"km%2Fh\"  relative to the earth surface, \r
\n" ); document.write( "\n" ); document.write( "then for the person the wind seems to have velocity  ((u-r)*i, (v-s)*j).\r
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\n" ); document.write( "\n" ); document.write( "Thus we have the equations for the unknowns wind's velocity components (u*i, v*j)\r
\n" ); document.write( "\n" ); document.write( "u - 7 = 9       (for i-direction),   and \r
\n" ); document.write( "\n" ); document.write( "v - 3 = 10     (for j-direction).\r
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\n" ); document.write( "\n" ); document.write( "It gives for the wind's velocity components   u = 7+9 = 16 \"km%2Fh\"  for i-direction,   and   v = 3+10 = 13 \"km%2Fh\"  for j-direction.\r
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\n" ); document.write( "\n" ); document.write( "Hence.  the speed of the wind is   \"sqrt%2816%5E2+%2B+13%5E2%29\" = \"sqrt%28425%29\" = 20.6 \"km%2Fh\".\r
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