<p>[Screen</a> shot 2010-04-28 at 9.32.15 PM.png](<a href=“http://cl.ly/jrm]Screen”>http://cl.ly/jrm)</p>
<p>How do you do this?</p>
<p>What I do is create a quadrilateral with x by extending the lines in A and C.</p>
<p>But… are there any theorems or anything for this type of shape? It’s on many SATs.</p>
<p>There’s a much easier way to do this problem. In the smaller size triangle, label the other vertex as D. So, now you know that, angle DAC and angle DCA add up to 40 (180-140). Additionally, you know that angle BAD and angle BCA add up to 50. With this information, angles BAC and BCA add up to 90. Thus x = 90 (180 - 90).</p>
<p>Hope that helps.</p>
<p>or you can bisect the 140 degree angle and draw an altitude to the base of the triangle.<br>
that will allow you to figure out that the combined bottom left angle of the whole triangle is 40, the combined bottom right angle is 50. So than you just do 180 - (40+50) = 90 = x</p>
<p>also, jw what the difficulty level is on this problem? it is a m or h?</p>
<p>How do you know that the triangle with 140 degrees is isosceles? This problem seems faulty. I got x=90 based on the assumption that the lower triangle is isos.</p>
<p>^ It doesn’t have to be isosceles by any means. You could have picked 30 and 10 for inner triangle. Then it would still end up giving you 90.</p>
<p>^you’re right. lol. I’m dumb.</p>