 # Area.

## Presentation on theme: "Area."— Presentation transcript:

Area

Back to Area: We can calculate the area between the x-axis and a continuous function f on the interval [a,b] using the definite integral: Where f(xi*) is the height of a rectangle and ∆x is the width of that rectangle. {(b-a)/n (n is the number of rectangles)} Remember that the area above the axis is positive and the area below is negative.

Set up the integral needed to find the area of the region bounded by: and the x-axis.

Set up the integral needed to find the area of the region bounded by: , the x-axis on [0,2].

Area bounded by two curves
Suppose you have 2 curves, y = f(x) and y = g(x) Area under f is: Area under g is:

Superimposing the graphs, we look at the area bounded by the two functions:
(top - bottom)*∆x

The area bounded by two functions can be found:

Find the area of the region between the two functions: and
Bounds? [-1,2] Top Function? Bottom Function? Area? = 9

Find the area bounded by the curves: and
Solve for bounds:

Find the area bounded by the curves: and
Sketch the graph: (top - bottom)*∆x

Find the area of the region determined by the curves: and
Bounds? In terms of y: [-2,4] Points (-1,-2) & (5,4) Graph? Solve for y:

Find the area of the region determined by the curves: and
Need 2 Integrals! One from -3 to -1 and the other from -1 to 5. Area?

Bounds? In terms of y: [-2,4] Right Function? Left Function? Area? = 18

In General: Vertical Cut: Horizontal Cut:

Find the Area of the Region bounded by and
Bounds? [0,1] Top Function? Bottom Function? Area?

Find the Area of the Region bounded by , , and the y-axis
Bounds? [0,π/4] and [π/4, π/2] [0,π/4] Top Function? Bottom Function? Area?

Find the Area of the Region bounded by , , and the y-axis
Bounds? [0,π/4] and [π/4, π/2] Top Function? Bottom Function? Area?

Find the area of the Region bounded by
Bounds? Interval is from -2, 5 Functions intersect at x = -1 and x = 3 Graph? Top function switches 3 times! This calculation requires 3 integrals!

Find the area of the Region bounded by

Find T so the area between y = x2 and y = T is 1/2.
Bounds? Top Function? Bottom Function? Area? Taking advantage of Symmetry Area must equal 1/2: Ans: