ch.8 geometry 1 Flashcards
difference between complementary angles & supplementary angles
complementary - 2 angles that add up to 90* (e.g. 48 and 42)
supplementary - 2 angles that add up to 180* (e.g. 125 and 55)
sum of angles in a triangle?
180 degrees
sum of angles in a circle?
360 degrees
sum of angles in a quadrilateral?
360 degrees
what are similar triangles?
triangles that look alike but are not the same
what are congruent triangles?
triangles that look alike, same size - exactly same shape and size
how do yk if a triangle is congruent?
- sss (3 sides in one triangle = 3 sides in the other)
- sas (2 sides and included angle in one triangle = 2 sides and included angle in other)
- asa (2 angles and side between them are equal in measure in each)
important parts of a right-angled triangle and their definitions
- hypotenuse: longest side, opposite right angle
- opposite: side across from a given angle
- adjacent: side next to a given angle
what is the pythagoras theorem?
in a right-angled triangle, the square on the hypotenuse is equal to the sum of the squares on the other 2 sides
what is the theorem of pythagoras in algebra?
a2 = b2 + c2
what is the converse of the pythagoras theorem?
if the square on one side of a triangle is equal to the sum of the squares on the other 2 sides, then the angle opposite the first side is a right angle
line segment
the line segment [AB] starts at A and ends at B
A •———–• B
ray (line)
the line that starts at A and continues on through B is called the ray [AB
A •————-•B———->
collinear (lines)
points that lie on the same line are said to be collinear
A •—————•B———-•C——-
intersect (lines)
the lines l and m intersect at the point p
l \p/ m
/ \
