fi Flashcards
ways to determine a plane
3 noncolinear points
a line and a point not on the line
2 intersecting lines
2 parallel lines
if a line intersects a plane not containing it…
then the intersection is exactly one point
if 2 planes intersect…
their intersections is exactly one line
If a line is perpendicular to 2 lines thru the foot…
then it is perpendicular to the plane
If a line is perpendicular to a plane…
then it is perpendicular to every line thru the ft
a line is perpendicular to a plane if…
it is perpendicular to every one of the lines that pass thru its ft
A line and a plane are parallel if…
they do not intersect
two planes are parallel if…
they do not intersect
what are skew lines
non-coplanar, non-parallel lines
T/F: if a plane contains one of two skew lines, it contains the other
False
T/F: If a line and a plane never meet, they are parallel
true
T/F: If two parallel lines lie in different planes, the planes are parallel
False
T/F: If a line is perpendicular to two planes, the planes are parallel
true
T/F: If a plane and a line not in the plane are each perpendicular to the same line, they are parallel to each other
True
the measure of an exterior angle of a triangle is equal to
the sum of the measure of the remote interior angles
a segment joining the midpoints of 2 sides of triangle is…
parallel to the 3rd side and its length is 1/2 the length of the third side
If 2 angles of one triangle are congruent to 2 angles of a second triangle…
then the 3rd angles are congruent
(AKA NO CHOICE THEOREM)
pentagon
5 sides
hexagon
6 sides
heptagon
7 sides
octagon
8 sides
nonagon
9 sides
decagon
10 sides
dodecagon
12 sides
pentadecagon
15 sides
n-gon
number
regular polygon is
equilateral and equiangular
1 3
x a
— = —
y b
2 4
what are the means and what are the extremes
numbers referring to terms
means: 2nd and 3rd
extremes: 1st and 4th
if the product of a pair of non-zero numbers is equal to the products of another pair of non-zero numbers then…
either pair of numbers may be made the extremes and the other pair the means of a proportion
JUST REFER TO THE SLIDE SO THIS MAKES SENSE
corresponding angles of similar triangles are…
congruent
coresponding sides of similar triangles are…
proportional
the altitude is drawn to the hypotenuse of a right triangle then…
3 similar triangles are produced
concentric circles
share the same center
congruent circles
circles are congruent if they have congruent radii
chord
segment that joins any 2 points on the circle
diameter
chord that goes through the center of the circle
if a radius is perpendicular to a chord then…
it bisects the chord
If a radius of a circle bisects a chord then…
is it perpendicular to that chord
If a line is the perpendicular bisector of a chord then…
it passes through the center of the circle