2. subtraction

4. 7
60
10

6. Day 13 ­ Proving that a quad is a rectangle or rhombus
We already looked at how to prove that a quad is a parallelogram:
both pairs opp sides ||
both pairs opp sides ≅
one pair opp sides both || and ≅
both pairs opp angles ≅
diagonals bisect each other
The symbol is only used for parallelogram.

7. In order to prove that a quadrilateral is a rectangle or rhombus,
YOU MUST FIRST SHOW THAT IT IS A PARALLELOGRAM.
Then, it only takes one more condition to make it a rectangle or rhombus.
A with ≅ diagonals rectangle
A with one rt angle rectangle
A with diagonals rhombus
A with one pair consecutive ≅ sides rhombus
A with a diagonal that bisects opposite angles rhombus

9. Example Proof:
A B Given: AD DC
BC DC
AD ≅ BC
D C Prove: ABCD is a rectangle