Download The Slope Formula

The Distance Formula
𝑑 = √(𝑥2 − 𝑥1 )2 + (𝑦2 − 𝑦1 )2

Used to find the length of a line
The Midpoint Formula
 x1  x2 y1  y2 
M
,

 2
2 


Used to determine if line segments bisect each other
Find the center of a circle
The Slope Formula
m
y 2  y1
x 2  x1


Used to determine if lines are parallel (same slope)
Used to determine if lines are perpendicular (negative reciprocal slopes)
Slope-Intercept Form of the Equation of a Line
y  mx  b
slope
y-intercept
Point-Slope Form of the Equation of a Line
Point-Slope Form of the Equation of a Line:
y  y1  m  x  x1 
m = slope
The Equation of a Circle:
 x  h
 h, k  =
2
  y  k   r2
center
2
r = radius
(x1,y1) = a point on the line
Common Core Geometry Formulas to Remember
Altitude Rule
 The altitude is the mean proportional between
the measures of the segments of the
hypotenuse
Leg Rule
 Each leg of a right triangle is the mean
proportional between the whole hypotenuse
and the projection of the leg on the
hypotenuse.
H L

L S
S A

A S
Trigonometry
The three trigonometric ratios compare these sides from the point of view of one of the acute angles (not the
right angle) in a right triangle:
Use this phrase to memorize the
three trigonometric ratios:
𝒔𝒊𝒏 (𝒂𝒄𝒖𝒕𝒆 ∡) =
𝒐𝒑𝒑𝒐𝒔𝒊𝒕𝒆
𝒉𝒚𝒑𝒐𝒕𝒆𝒏𝒖𝒔𝒆
𝒄𝒐𝒔 (𝒂𝒄𝒖𝒕𝒆 ∡) =
𝒂𝒅𝒋𝒂𝒄𝒆𝒏𝒕
𝒉𝒚𝒑𝒐𝒕𝒆𝒏𝒖𝒔𝒆
𝒕𝒂𝒏 (𝒂𝒄𝒖𝒕𝒆 ∡) =
𝒐𝒑𝒑𝒐𝒔𝒊𝒕𝒆
𝒂𝒅𝒋𝒂𝒄𝒆𝒏𝒕
SOH
CAH
TOA
Convert Degrees to Radians (vice versa)

To convert from degrees to radians MULTIPLY BY

To convert from radians to degrees
Arc Length Formula
Formula:
s r
MULTIPLY BY
𝜋
180
180
𝜋
Area of a Sector Formula
Formula:
A
1 2
r
2