two geometrical proofs

an intention for this work is to put up statements, in a deductive order and for students to think about and then hopefuly give reasons for these statements

a ppt for the regular pentagon is here
a ppt for a triangle (and congruence) is here
both of these are entirely rigorous

it's just that one of them is false....

the first is from Tony Gardiner, involving a regular pentagon
leading to (a well known) result derived from similar triangles
I very much like the way that Tony has structured this, so that statments build upon each other

in this case, students establish that EB is parallel to DC by considering angles















the second is fairly well known
it helpfully uses congruency conditions

a recap on congruency conditions for triangles before using these