document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=247562>Question 247562</A>: <I><SPAN STYLE=\"word-break: break-all;\"> An airplane is sighted at the same time by two ground observers who are 4 miles aparts and both directly west of the airplane. They report the angles of elevation as 15 degrees and 20 degrees. How high is the airplane? </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #180583 by </B><A HREF=/tutors/aboutme.mpl?userid=stanbon><B>stanbon(75887)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=stanbon><IMG SRC=http://www.algebra.com/images/aboutme-small.gif BORDER=0 alt=\"About Me\" VALIGN=MIDDLE></A>&nbsp;<IMG SRC=http://www.algebra.com/images/nopicture.jpg><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=180583\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> An airplane is sighted at the same time by two ground observers who are 4 miles aparts and both directly west of the airplane. They report the angles of elevation as 15 degrees and 20 degrees. How high is the airplane?<BR>\n" );
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document.write( "Draw the picture.<BR>\n" );
document.write( "You have two overlapping right triangles.<BR>\n" );
document.write( "the larger base is x miles to the west of a point beneath the plane. <BR>\n" );
document.write( "ne observer is 21120 west of a point directly beneath the plane.<BR>\n" );
document.write( "The other observer is x ft west of the same point.<BR>\n" );
document.write( "Let the altitute of the plane be \"h\"<BR>\n" );
document.write( "----<BR>\n" );
document.write( "Equations:<BR>\n" );
document.write( "tan(15)= h/x<BR>\n" );
document.write( "tan(20) = h/(x-21120)<BR>\n" );
document.write( "---------------------------<BR>\n" );
document.write( "h = x*tan(15)<BR>\n" );
document.write( "h = (x-21120)*tan(20)<BR>\n" );
document.write( "==========================<BR>\n" );
document.write( "x*tan(15) = x*tan(20) - 21120*tan(20)<BR>\n" );
document.write( "x = [-21120*tan(20)]/[tan(15)-tan(20)]<BR>\n" );
document.write( "x = -7687.05/-0.0960 = 80055.89<BR>\n" );
document.write( "---------------<BR>\n" );
document.write( "h = x*tan(15)<BR>\n" );
document.write( "h = 21,450.9 ft. (height of the airplane)<BR>\n" );
document.write( "===============<BR>\n" );
document.write( "Cheers,<BR>\n" );
document.write( "Stan H. </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );