document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=206765>Question 206765</A>This question is from textbook <A HREF=http://www.amazon.com/exec/obidos/ASIN/1405802111/algebrahomeworkh>Longman Mathematics For IGCSE book1</A><BR>\n" );
document.write( ": <I><SPAN STYLE=\"word-break: break-all;\"> In a quadrilateral ABCD, AB=3cm, BC=5.7cm, CD=4cm and AD=4cm. AngleB=angle D=90 degree. Calculate the angle at A to 1 decimal place.\r<BR>\n" );
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document.write( "This question is from the chapter trigonometry:Tangent ratios.<BR>\n" );
document.write( "Please do help me solving this question. It is really difficult for me. Thankyou very much indeed! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #156296 by </B><A HREF=/tutors/aboutme.mpl?userid=mickclns><B>mickclns(59)</B></A><img src=\"/images/stars/stars-08.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=mickclns><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=156296\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=drawing%28300%2C300%2C0%2C8%2C0%2C8%2C%0D%0A+++line%282%2C2%2C2%2C6%29%2C%0D%0A+++line%282%2C2%2C6%2C2%29%2C%0D%0A+++line%282%2C6%2C3.9%2C6.7%29%2C%0D%0A+++line%283.9%2C6.7%2C6%2C2%29%2C%0D%0A+++red%28+line%282%2C6%2C6%2C2%29+%29%2C%0D%0A%0D%0A+++line%282%2C2.5%2C2.5%2C2.5%29%2C%0D%0A+++line%282.5%2C2%2C2.5%2C2.5%29%2C%0D%0A%0D%0A+++line%283.47%2C6.52%2C3.67%2C6.16%29%2C%0D%0A+++line%284.09%2C6.31%2C3.67%2C6.16%29%2C%0D%0A%0D%0A+++locate%281.7%2C1.9%2CD%29%2C%0D%0A+++locate%285.8%2C1.9%2CC%29%2C%0D%0A+++locate%281.7%2C6.2%2CA%29%2C%0D%0A+++locate%283.75%2C7.2%2CB%29%0D%0A%29+ ALIGN=MIDDLE   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "Since AD=CD and angle D is a right angle, Triangle ADC is an isosceles right triangle so angles DAC and  DCA are 45 degrees.<BR>\n" );
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document.write( "The tangent of angle BAC (by SOH-CAH-TOA) is <IMG STYLE=\"max-width:80%;\" SRC=/cgi-bin/plot-formula.mpl?expression=opposite%2Fadjacent+=+BC%2FBA+=+5.7%2F3+=+1.9 ALIGN=MIDDLE  ALT=\"opposite%2Fadjacent+=+BC%2FBA+=+5.7%2F3+=+1.9\"   DISABLED_style= \"max-width:90%; height:auto;\" ><BR>\n" );
document.write( "so the measure of angle BAC is arctan(1.9) = 62.2    On your calculator, arctan or inverse tangent is on the same button as tan, and looks like tan to the -1 power (which it isn't).\r<BR>\n" );
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document.write( "So the angle at A is the sum of the angles DAC and BAC which is 45 + 62.2 = 107.2 degrees. </SPAN>\n" );
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