document.write( "<A HREF=/cgi-bin/jump-to-question.mpl?question=690163>Question 690163</A>: <I><SPAN STYLE=\"word-break: break-all;\"> This problem is the first three dimensional problem I have seen, and I'm having a lot of trouble with it. I would have tried it, but I didn't know where to start! The problem is this:<BR>\n" );
document.write( "Given:<BR>\n" );
document.write( "segment AP is perpendicular to plane M<BR>\n" );
document.write( "segment AB is congruent to segment AC<BR>\n" );
document.write( "Prove:<BR>\n" );
document.write( "triangle BPC is isosceles.<BR>\n" );
document.write( "Diagram:<BR>\n" );
document.write( "(my best description)<BR>\n" );
document.write( "A plane M is shwn.<BR>\n" );
document.write( "B, P, and C are all points on plane M. They connected to form a triangle.<BR>\n" );
document.write( "A is a point that looks to be straight above point P. From the given information, I can deduce that point A actually is right above point P.<BR>\n" );
document.write( "Together, points A, B, C, and P create a triangular prism.\r<BR>\n" );
document.write( "\n" );
document.write( "What I've reasoned:<BR>\n" );
document.write( "angle ABC is congruent to angle ACB because of the Isosceles Triangle Theorem.<BR>\n" );
document.write( "angle APC is a right angle.<BR>\n" );
document.write( "triangle APC is a right triangle.\r<BR>\n" );
document.write( "\n" );
document.write( "I have no clue how to approach this, please help! </SPAN>\n" );
document.write( "</I><HR><TABLE width=100%><TR><TD><B><A HREF=http://www.algebra.com/>Algebra.Com's</A> Answer #426198 by </B><A HREF=/tutors/aboutme.mpl?userid=DrBeeee><B>DrBeeee(684)</B></A><img src=\"/images/stars/stars-11.gif\" alt=\"\" >&nbsp;<A HREF=/tutors/aboutme.mpl?userid=DrBeeee><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=426198\">put this solution on YOUR website!</A><BR><SPAN STYLE=\"word-break: break-all;\"> Continue your correct reasoning.<BR>\n" );
document.write( "Since AB = AC (isosceles triangle ABC))<BR>\n" );
document.write( "AP = AP Identity<BR>\n" );
document.write( "Your right triangles<BR>\n" );
document.write( "BPA and CPA are congruent<BR>\n" );
document.write( "Then<BR>\n" );
document.write( "BP = CP legs of congruent triangles<BR>\n" );
document.write( "Therefore<BR>\n" );
document.write( "Triangle BPC is an isosceles triangle (two legs are equal) </SPAN>\n" );
document.write( "</TD></TR></TABLE>\n" );