6.1 Area Between 2 Curves Wed March 18 Do Now Find the area under each curve in the interval [0,1] 1) 2)
Dec 19, 2015
6.1 Area Between 2 CurvesWed March 18
Do Now
Find the area under each curve in the interval [0,1]
1)
2)
Graphing Calculator - Integrals
• This only works if you have bounds
• Math -> 9 fnint(
• Fnint(equation,x,lower,upper)
Test Review
• Retakes by?
Area Between 2 Curves
• If f(x) > g(x) on the interval [a,b], then the area between f(x) and g(x) on the interval [a,b] is
Area Between 2 Curves
• 1) Graph both functions
• 2) Decide which function is f(x) and which is g(x)
• 3) Evaluate each integral on the given interval
• 4) Subtract the 2 values
Examples
Find the area between the curves on the interval [0,2]
Example 2
• Find the area between the curves on the interval [1,3]
Area between 2 Curves that Cross
• If the curves cross inside a given interval, we need to split it up at the intersection point.
• Set the 2 functions equal to each other to find the intersection point.– Can use the graphing calculator to find
intersection points
Ex
• Ex: Find the area bounded by the graphs on the interval [0,2]
You try
• 1) Find the area of the region in the interval [1, 3] between the functions
• 2) Find the area in the interval [-2, 5] between the functions
Closure
• Hand in: Find the area between the curves on the interval [0,2]
• HW: p.361-2 #1,2, 5, 8, 9, 16
6.1 Area Bounded by CurvesThurs March 19
• Do Now
• Find the area between the 2 curves on the [0,5]
• 1)
• 2)
HW Review: p.361 #1,2, 5, 8, 9, 16
• 1) 102
• 2) 34/3 = 11.333
• 5)
• 8) 262/3 = 87.333
• 9)
• 17) 2 – pi/2 = .429
Area Between 2 Curves that Intersect (no given interval)
• 1) Set f(x) = g(x)
• 2) Solve for x– The two x values are your lower and upper
bounds
• 3) Evaluate the area between the 2 curves
• Calculator: use graphs to find intersection points
Using a Calculator
• Graph both functions
• 2nd -> calc -> intersect
• Pick the 2 curves you want to find the intersection of
• Guess: pick a point near the intersection point
Examples
• Find the area bounded by the graphs of
Ex 2
• Find the area bounded by the graphs of
Areas determined by 3 Curves
• If the upper or lower curve changes from one function to another, we split it up into 2 or more areas
• Ex:
You try
• Find the area of the region that is enclosed between the curves
You try
• Find the area bounded by the graphs of
Closure
• Hand in: Find the area of the region that is enclosed between the curves
• HW: p.361 #3 4 10 13 27 29 31
6.1 Area PracticeFri March 20
• Do Now
• Calculate the area determined by the intersections of the curves
HW Review: p. 361 #3 4 10 13 27 29 31
• 3) 32/3 = 10.667
• 4) 128
• 10) 12ln6 – 10 = 11.501
• 13) 160/3 = 53.333
• 27) 64/3 = 21.333
• 29) 2
• 31) 128/3 = 42.667
Practice
• (green book) worksheet p.409 #7-12, 15-20, 30-34
Closure
• Find the area enclosed by the following
• HW: worksheet p.409 #7-12 15-20 30-34
6.1 Areas with Respect to YMon March 23
• Do Now
• Find the area bounded by the following functions
HW Review: p.409 #7-12
• 7) 4.86
• 8) 20.65
• 9) 3
• 10) 31/6 = 5.167
• 11) 29/2 = 14.5
• 12) 12
HW Review: p.409 #15-20
• 15) 1/6 = .167
• 16) 36
• 17) 27/4 = 6.75
• 18) 27/4 = 6.75
• 19) 1/12 = .083
• 20) 1/3 = .333
HW Review: p.409 #30-34
• 30) 4/3
• 31) 1
• 32) 4
• 33) 8
• 34) 32/3
Integrating with Respect to Y
• If f(y) is to the right of g(y), then the area between two curves is
• 1) Set all functions x = f(y) and x = g(y)• 2) The curve on the right is f(y)• 3) Evaluate the areas and subtract
Revisiting Previous Example
• Let’s integrate with respect to y instead of splitting the area up into 2 areas.
Example 1.6
• Find the area bounded by the graphs of
Closure
• Hand in: Sketch and find the area bounded by the given curves. Choose the variable of integration so that the area is written as a single integral
• HW: p.363 #19-26 skip 24• Quiz Fri
6.1 Area ReviewTues March 24
• Do Now
• Sketch and find the area of the region bounded by the given curves.
HW Review: p.363 #19-26
• 19) 1331/6 = 221.833
• 20) 64/3 = 21.333
• 21) 256
• 22) 81/2 = 40.5
• 23) 32/3
• 25) 64/4
• 26) 3
Area Review
• Area between 2 curves• F(x) - G(x)• Finding intersection points = bounds
• Area inside 3 curves– Splitting up into 2 areas
• What are the bounds of each area?
– Integrating with respect to Y• Using Y - bounds, and Y - functions
Practice
• (blue book) Worksheet p.448 #1-4, 7-13 odds
Closure
• Journal Entry: When trying to find the area between two curves, when should we integrate with respect to x? to y? Would you rather switch between x and y, or have to split your area problem into several problems? Why?
• HW: Finish worksheet p.448 #1-6 all, 7-13 odds
• Quiz Fri March 27
6.1 Quiz Review Wed March 25
• Do Now
• Find the area of the region R between the curves
• 1) y = 2x + 1, y = 0, y = -x
• 2) y = x^2, y = -x + 2, y = 0
HW Review: worksheet p.448 #1-6, 7-13 odds
• 1) 9/2 11) sqrt 2• 2) 22/3 13) 1/2• 3) 1 19) 37/12• 4) 10/3 21) ~5.66• 5) 32/3• 6) 9• 7) 49/192• 9) 1/2
Area Review
• Area between 2 curves• F(x) - G(x)• Finding intersection points = bounds
• Area inside 3 curves– Splitting up into 2 areas
• What are the bounds of each area?
– Integrating with respect to Y• Using Y - bounds, and Y - functions
Quiz
• All types of areas
• Can use graphing calculator, but must set up the integral correctly first
• Show all work used to set up the integral
Practice
• (oj) worksheet p.395 #1-6 9 10 13-17
Closure
• How can you find the area between 2 or more curves? How can you find the bounds?
• HW: Finish worksheet p.395 #1-10 13-17
• 6.1 Quiz Fri
Area ReviewThurs March 26
• Do Now
• Find the area bounded by the following:
• Y = 8x – 10
• Y = x^2 - 4x +10
Area
• 1) Graph all the functions• 2) Shade the region bounded by the
functions• 3) If possible, split up into several areas• 4) For each area: Integrate higher – lower
– Bounds = intersection points (smallest – largest)
– Calculator
HW Review: worksheet p.395 #1-10 13-17
• 1) 1.571 10) 0.833
• 2) 4.189 13) 16
• 3) .0833 14) 8.167
• 4) 1.333 15) 10.667
• 5) 8.533 16) 10.667
• 6) 1.467 17) 4
• 9) 0.833
Area Review 6 problems
• Area between 2 curves• Higher curve – lower curve• Finding intersection points = bounds
• Area inside 3 curves– Splitting up into 2 areas
• What are the bounds of each area?
– Integrating with respect to Y• Using Y - bounds, and Y - functions
You try
• The area bounded by y = sqrt x, y = -sqrt x, and y = 1 - x
Quiz
• All types of areas
• Can use graphing calculator, but must set up the integral correctly first
• Show all work used to set up the integral
Closure
• How can you find the area between 2 or more curves? How can you find the bounds? When would you integrate with respect to x or y?
• 6.1 Quiz tomorrow