Theorem 9

Theorem 9: A quadrilateral is a rhombus if and only if the diagonals bisect all the vertex angles.

1. Given:

ABCD is a rhombus

To prove:

/ DAC = / BAC
/ ABD = / CBD
/ BCA = / DCA
/ CDB = / ADB

2. Given:

/ DAC = / BAC
/ ABD = / CBD
/ BCA = / DCA
/ CDB = / ADB

To prove:

ABCD is a rhombus

1. Given:	ABCD is a rhombus
To prove:	/ DAC = / BAC / ABD = / CBD / BCA = / DCA / CDB = / ADB

2. Given:	/ DAC = / BAC / ABD = / CBD / BCA = / DCA / CDB = / ADB
To prove:	ABCD is a rhombus