A N ANGLE BISECTOR IS THE RAY THAT DIVIDES ( OR BISECTS ) AN ANGLE INTO CONGRUENT ADJACENT ANGLES. O M G N
H OW CAN WE USE THIS INFORMATION ABOUT ANGLE BISECTORS ? (x+40)° (3x – 20)° P Q RS
A MIDPOINT IS THE POINT THAT DIVIDES ( OR BISECTS ) THE LINE SEGMENT INTO EQUAL PARTS. T HE EQUAL PARTS ARE ALSO CALLED CONGRUENT SEGMENTS. D E3 m L To Bisect means to divide in ½ DL = LE To be congruent means to be equal
D ON ’ T FORGET ABOUT ANGLE ADDITION AND SEGMENT ADDITION POSTULATES !
C AN WE BISECT A LINE ? W HY OR WHY NOT ? Take a minute to write down your response.
B ACK TO MIDPOINTS! You will sometimes see midpoints on a coordinate plane. The MIDPOINT FORMULA will allow you to find the x and y coordinates for the midpoint. P(1,2) Q(3,-2) How do we find that midpoint?
MIDPOINT FORMULA The x for the midpoint = The y for the midpoint = Add the 2 and divide by 2 (sound familiar?)
L ET ’ S PRACTICE THE M IDPOINT F ORMULA A (5, 4) and B(3, 2) A(-1, -9) and B(11, -5) A(6, -4) and B(1, 8) C(3, 0) and M(3,4) D(5,2) and M(7,6) E(-4,2) and M(-3,-2) FIND THE MIDPOINT (M) FIND THE ENPOINT