12.7.12
First thing to know is what is a trapezoid.
- A trapezoid has exactly one pair of parallel lines
Properties of trapezoids
- Trapezoid Consecutive Angles Conjecture -The consecutive angles between the bases of a trapezoid are 180 degrees (supplementary).
2. Isosceles Trapezoid Conjecture
- The base angles of an isosceles trapezoid are congruent.
<A is congruent to <D.
Try solving this: Find x.
1st step: 2x+5=3x+2
2nd step:subtract 2x from both sides
Equation should look like this: 5=x+2
3rd step: subtract 2 from both sides and you get your answer.
Answer is 3+x
* You don't do this to 4x-2 and 5x+3 because those are parallel not congruent.
1st picture from http://www.google.com/imgresum=1&hl=en&tbo=d&biw=1517&bih=693&tbm=isch&tbnid=sGz7fgFw41GoMM:&imgrefurl=http://www.ck12.org/concept/Trapezoids---Intermediate/&docid=eeMQ8dVhvkcDNM&imgurl=http://www.ck12.org/flx/show/image/user%25253Ack12editor/201209241348511282764513_dff7a8f97ef56047035788567c45fc33-201209241348512460267699.png&w=708&h=511&ei=MabCUMukGPC10AGlqYG4Aw&zoom=1&iact=hc&vpx=4&vpy=274&dur=292&hovh=191&hovw=264&tx=128&ty=97&sig=108818101793549926599&page=2&tbnh=145&tbnw=202&start=27&ndsp=38&ved=1t:429,r:42,s:0,i:215
2nd picture from http://www.geom.uiuc.edu/~dwiggins/conj22.html
WHAT ARE THE RHOMBUS'S CONJECTURES?