Page 89 - TB_6B
P. 89
25 Find the Angle’s Partner
The following table shows the positions of 2 lines in a plane.
Intersecting lines Parallel lines are lines Perpendicular lines
meet or cross each in a plane that never
other. intersect. intersect to form right
angles.
EI
A B P
F C D N
HG
M Q
Line EG and line HI Line AB is parallel Line MN is
intersect at point F. to line CD. perpendicular to
line PQ.
AB CD
MN PQ
When 2 lines intersect, 4 angles are formed. adc
Angles that are across from each other, such b
as a and c or b and d, are called
vertical angles.
In 600 B.C., a Greek mathematician, Thales, proved that vertical angles
are congruent.
m a = 180 m b, and m c = 180 m b.
So, a and c are congruent. The same method
can be used to prove that b and d are congruent.
Vertical angles are congruent.
78
The following table shows the positions of 2 lines in a plane.
Intersecting lines Parallel lines are lines Perpendicular lines
meet or cross each in a plane that never
other. intersect. intersect to form right
angles.
EI
A B P
F C D N
HG
M Q
Line EG and line HI Line AB is parallel Line MN is
intersect at point F. to line CD. perpendicular to
line PQ.
AB CD
MN PQ
When 2 lines intersect, 4 angles are formed. adc
Angles that are across from each other, such b
as a and c or b and d, are called
vertical angles.
In 600 B.C., a Greek mathematician, Thales, proved that vertical angles
are congruent.
m a = 180 m b, and m c = 180 m b.
So, a and c are congruent. The same method
can be used to prove that b and d are congruent.
Vertical angles are congruent.
78
