Concepts Pt 2. Flashcards
What’s a parallelagram
equal parallel sides
What happens to the the area of a rectangle with a constant perminiter when…
Area increases as L/W become more similar and is maxed when the rectangle is square
What;s a trapazoid
unequal parallel sides
Don’t assume your polygon is regular instead…
Use n-2 (180º)
Equalaterial Triangle
Evey angle is 60º
isosceles right triangle
-have 2 equal sides and therefore two equal angles
- has sides 1:1:√2
45-45-90
To find the area of a central angle…
try to dind what proportion of the cirecle that area covers, then find total circle area
Minor Arc
is the short way around the circle
Major Arc
the long way around a circle
An inscribed Angle
this is an angle that starts on one side of the circle instead of in the center of the circle.
-It is always 1/2 the central anfle
Pathagrean Triples
3, 4, 5
5, 12, 13
8, 15, 17
7, 24, 25
The Third Side Rule
any side of a triangle must be greater than the diffrence of the other two sides and less than their sum.
Ex: sides A = 10 B= 13 Side C must be between: 13+10 = 23 13-10= 3 23 > C > 3
Within any triangle, the larger the angle….the ___ the side opposite that angle
the longer the side opposite that angle
How are Coordinates writen
A) x, y
B) y, x
A) x, y
Is this coordinate on this line? How could you tell?
Plug it in and check! Ex: y = 3x + 5 (8,2) y = 3(8) + 5 y = 24 + 5 y = 29 Therrfore no
Parabolas What does eveything mean?
y = (x-h) ^2 + k
y = (x-h) ^2 + k
- h, k is the location of the vertex
- be very careful of the sign in front of the h! Since H is normally subtracted, a sign flip could mean the vertex sits in the negative colum.
Example
y = (x+3)^2 +3
The vertex is -3, 3
What’s the relationship between two perpendicular slopes
Two perpendicular slopes (right angle) have reciprical slopes. If one is 2 then the other is -1/2. (note the negative!)
What is 50 as a percent of 30
This means What percent of 30 is 50?
50/30 x 100 = 166%
12 is 5% of x
12 = 0.05x
With different percent increases make equations
Ex: if K was increased 20%
= k + 02.k
X is reduced by 30%
=70%x
36 is x% more than 24
36 = 24 + (x%)24 –> 0.5 = x%
When writing percents, make sure to write x/100 and not x
This is so you know that the final number is 300% and not 3%
When using percent diffrence, be very careful of what your original percent is
-Ex: x is what percent more than y?
= (diffrence/original) x 100
= (x-y / y) x 100
A 30-60-90 triangle has sides in a ratio of
A 30-60-90 triangle has sides in a ratio of x:x√3:2x, with the 1x side opposite the 30 degree angle.
Arc length of a sector
= radius x degrees of central angle / 360
