Algebra II (Lesson 1.4 ~ 2013­2014) .notebook
November 13, 2013
Common Formulas
Formula: equation that relates two or more quantities usually
Do not copy
represented by variables on page 26
Formula
Quantity
Lesson 1.4
Rewrite Formulas and Equations
Meaning of Variables
Distance
d = rt
d: distance, r: rate, t: time
Temperature
F = (9/5)C + 32
F: Fahrenheit, C: Celsius
Area of Triangle
A = (1/2)bh
A: area, b: base, h: height
Area of Rectangle
A = lw
A: area, l: length
w: width
Perimeter of Rectangle
P = 2l + 2w
P: Perimeter, l: length, w: width
Area of Trapezoid A = (1/2)(b1 + b2)h
A: Area, b : base 1
1
b : base 2, h: height
2
Area of Circle
A = π r
2
A: area, r: radius Circumference
C = 2πr
C: circumference r: radius
Solving for a Variable
Different Formula
This means to rewrite an equation in terms of a different variable
The formula for the distance d between opposite vertices
of a regular hexagon is d = (2a/√3) where a is the distance
between opposite sides. Solve the formula for a. Then find
a when d = 10cm.
Rewrite C = 2π r in terms of r
Then find the radius of a circle
with a circumference of 44 in.
C = 2π r
d
a
Algebra II (Lesson 1.4 ~ 2013­2014) .notebook
November 13, 2013
Solve the formula for the variable in red. Then use the
given information to find the value of the variable.
Rewrite a Formula with Three Variables
Solve the formula P = 2l + 2w for w.
Then find width of the rectangle with a length of 12m
and perimeter of 41.
A = (1/2)bh
A=
b
1
P = 41m
12m
w
h
Solve 9x - 4y = 7 for y.
Then find the value of y when x = -5.
h
b
Find h if b = 12m
and A = 84m2
Rewrite a linear equation
1
(b + b2)h
2 1
b
2
Find h if b1 = 6in,
b2 = 8in, and A = 70in2
Rewrite a nonlinear equation
Solve 2y + xy = 6 for y.
Then find the value of y when x = -3.
What property do we need to use?
Algebra II (Lesson 1.4 ~ 2013­2014) .notebook
November 13, 2013
Solve the equation for y. Then find the value of y when x = 2.
Rewrite a nonlinear equation
y - 6x = 7
Solve 2xy - 5y = 8 for y.
Then find the value of y when x = 3.
3x + 2y = 12
Assignment #4
p. 30 3-6, 11-14, 16-30 even, 37
3 = 2xy - x