document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=1153642>Question 1153642</A>: <I><SPAN STYLE=\"word-break: break-all;\"> The angle of elevation of the top of a flag post from a point A on level ground is 13 degrees.The angle of elevation of elevation of the top of the flag post from another point B nearer the flag post and 120 m from A is 30 degrees. B is between A and the bottom of the flag post and the three points are collinear. Find:<BR>\n" );
document.write( " ( a)the distance from the point B to the top of the flag post.<BR>\n" );
document.write( "  (b)the height of the flag post. </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #775892 by </B><A HREF=/tutors/aboutme.mpl?userid=Cromlix><B>Cromlix(4381)</B></A><img src=\"/images/stars/stars-13.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=Cromlix><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/cgi-bin/show-face.mpl?user=Cromlix><BR>You can <A HREF=\"/cgi-bin/embed-solution.mpl?show=1&solution=775892\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Hi,<BR>\n" );
document.write( "First draw a right angled triangle CDB.<BR>\n" );
document.write( "CD will represent the flagpole (C at the top and D at the base.)<BR>\n" );
document.write( "DB will represent the length of ground between the base of the flagpole (D) and the point B<BR>\n" );
document.write( "Angle CDB will equal 30 degrees (given)<BR>\n" );
document.write( "Now, extend base line DB out and put an A at the end.<BR>\n" );
document.write( "Draw another line from the top of the flagpole C to A. This will form a second right angled triangle CDA.<BR>\n" );
document.write( "Angle CAD will equal 13 degrees (given)<BR>\n" );
document.write( "Now add angle CBA which is 180 - 30 deg. = 150 deg. (DA is a straight line)<BR>\n" );
document.write( "By deduction angle BCA = 180 -(150 + 30 deg) = 17 deg<BR>\n" );
document.write( "Consider triangle CBA<BR>\n" );
document.write( "Angle CAB = 13 deg, Angle CBA = 150 deg and Angle BCA = 17 deg.<BR>\n" );
document.write( "Using Sine Rule (a/Sin A = b/Sin b = c/Sin C)<BR>\n" );
document.write( "a/Sin A = c/Sinc<BR>\n" );
document.write( "a/sin13 = 120m/sin17<BR>\n" );
document.write( "Cross multiply<BR>\n" );
document.write( "a * sin17 = 120 * sin 13   (* means times)<BR>\n" );
document.write( "a = (120 x sin13)/sin 17 <BR>\n" );
document.write( "a = 92.3 m<BR>\n" );
document.write( "This is the distance from the point B to the top of the flagpost.\r<BR>\n" );
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document.write( "Now consider triangle CDB<BR>\n" );
document.write( "Side CB = 92.3 m  (the Hypotenuse)<BR>\n" );
document.write( "Angle DBC = 30 deg<BR>\n" );
document.write( "Using Trig Ratios (Sin = Opposite/Hypotenuse, Cos = Adjacent/ Hypotenuse and Tan = Opposite/Adjacent<BR>\n" );
document.write( "The height of the flagpost.(CD)<BR>\n" );
document.write( "sin30 = CD/CB<BR>\n" );
document.write( "sin30 = CD/92.3<BR>\n" );
document.write( "Cross multiply<BR>\n" );
document.write( "CD = sin30 * 92.3<BR>\n" );
document.write( "CD = 46.2 m (1 decimal place)<BR>\n" );
document.write( "Sorry its so long winded, but I hope it helps. :-)\r<BR>\n" );
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document.write( " </SPAN>\n" );
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