unit 7: similarities Flashcards
ratio
compares 2+ quantities, with the denominator being >0
proportion
an equation stating that 2 ratios are equivalent (“x is to y as a is to b” –> x/y = a/b)
extended proportion
when there are 3+ equivalent ratios
terms
objects of a proportion
means-extremes property of proportions
aka the “cross-product property”
if a/b=c/d, then ad=bc
properties of proportions
a/b=c/d
- ad=bc (cross multiply)
- a/c=b/d (divide cross-multiply 1&3)
- b/a=d/c (divide cross-multiply 4&3)
- (a+b)/d=(c+d)/d (1&2/4=3&4/4)
- a/b=c/d=e/f, then a+c+e/b+d+f=a/b
similarity
2 polygons are similar if when their vertices are paired,
1. their corresponding angles are congruent
2. their corresponding sides are proportional
angle angle similarity postulate
if 2 angles of 1 triangle are congruent to 2 angles of another triangle, then the 2 triangles are similar
triangle SAS similarity theorem
if an angle of 1 triangle is congruent to another triangle’s angle and the including sides of those angles are in proportion, then the triangle is similar
triangle SSS similarity theorem
if the sides of 2 triangles are proportional, then the 2 triangles are similar
CPSTP
Corresponding Parts of Similar Triangles are Proportional
triangle proportionality theorem
if a line is parallel to 1 side of a triangle and interests the 2 other sides, then it divides those sides proportionally
side splitter theorem
if 3 parallel lines intersect 2 transversals, then the segments intercepted on the transversals are proportional
triangle angle bisector theorem
if 2 rays bisect a triangle, then they’re dividing the opposite side into proportional segments to the 2 other sides