document.write( "Question 43142: Two planes leave an airport at the same time, one flying due west at 500km/h and the other flying due southeast at 300km/h. What is the distance between the planes two hours later? \n" ); document.write( "
Algebra.Com's Answer #28175 by psbhowmick(878)\"\" \"About 
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Note: Distance = Speed x Time\r
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\n" ); document.write( "\n" ); document.write( "In 2 hours, the plane travelling to West travels a distance of 500x2 = 1000 km.
\n" ); document.write( "In 2 hours, the plane travelling to South-East travels a distance of 300x2 = 600 km.\r
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\n" ); document.write( "\n" ); document.write( "If their initial position was the point O then their final positions, after 2 hours, are points A and B respectively.
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\n" ); document.write( "\n" ); document.write( "We need to know the length of AB.
\n" ); document.write( "In triangle BCO, as OB is in South-East direction.
\n" ); document.write( "So, \"OC%2FOB\" = cos(< BOC) = \"cos%2845%5Eo%29\"
\n" ); document.write( "or \"OC%2F600+=+cos%2845%5Eo%29\"
\n" ); document.write( "or \"OC%2F600+=+1%2Fsqrt%282%29\"
\n" ); document.write( "or \"OC+=+600%2Fsqrt%282%29\"
\n" ); document.write( "or \"OC+=+300sqrt%282%29\"
\n" ); document.write( "or OC = 424.264 km\r
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\n" ); document.write( "\n" ); document.write( "Therefore, AC = AO + OC = 1000 + 424.264 = 1424.264 km\r
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\n" ); document.write( "\n" ); document.write( "As BCO is a right angled isosceles triangle with \n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "Now, in triangle ACB, \n" ); document.write( "Applying Pythagorus theorem,
\n" ); document.write( "\"AB%5E2+=+AC%5E2+%2B+BC%5E2\"
\n" ); document.write( "or \"AB%5E2+=+1424.264%5E2+%2B+424.264%5E2\"
\n" ); document.write( "or \"AB%5E2+=+2208528.14\"
\n" ); document.write( "or \"AB+=+sqrt%282208528.14%29\"
\n" ); document.write( "or AB = 1486.112 km\r
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\n" ); document.write( "\n" ); document.write( "Hence, the reqd. distance between the two planes after 2 hours is 1486.112 km.
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