Is the Integral of f(t)*cost dt an Odd Function with Limits from -pi/2 to pi/2?

In summary, the function f(t) given by f(t) = 1 if -pi/2 <= t <= 0, -1 if 0 <= t <= pi/2, and 0 elsewhere, results in an odd function when multiplied by the cosine of t. This is because the product of an even function and an odd function is always odd.
  • #1
skan
15
0
f(t) = 1 if -pi/2 <=t <=0
-1 if 0<=t<= pi/2
0 elsewhere

how does integral of f(t)*cost dt become and odd function with the integral limit from - pi/2 to pi/2 ?

thanks a lot
 
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  • #2
skan said:
how does integral of f(t)*cost dt become and odd function with the integral limit from - pi/2 to pi/2 ?

It's not the integral of f(t)cos(t) that is odd (in fact it's just a number). It's the function f(t)cos(t) itself that is odd.

Let's see why.

Let y(t)=f(t)cos(t)
so, y(-t)=f(-t)cos(-t)

Note that f(-t)=-f(t) and cos(-t)=cos(t). So,

y(-t)=-f(t)cos(t),

and thus y(t) is odd. In general, the product of any even function and any odd function is odd.
 
  • #3
thanks a lot
 

1. What is an odd function?

An odd function is a function in which the value of the function at a negative input is equal to the negative of the value of the function at the corresponding positive input. In other words, if you take the negative of the input and plug it into the function, you will get the same value as you would if you plugged in the positive value. Graphically, an odd function is symmetric about the origin.

2. What is an even function?

An even function is a function in which the value of the function at a negative input is equal to the value of the function at the corresponding positive input. In other words, if you take the negative of the input and plug it into the function, you will get the same value as you would if you plugged in the positive value. Graphically, an even function is symmetric about the y-axis.

3. How do you determine if a function is odd or even?

To determine if a function is odd or even, you can use the rules for odd and even functions. If the function satisfies the rule for an odd function (f(-x) = -f(x)), then it is an odd function. If the function satisfies the rule for an even function (f(-x) = f(x)), then it is an even function. You can also look at the graph of the function and see if it is symmetric about the origin or the y-axis.

4. What are some examples of odd and even functions?

Some examples of odd functions include f(x) = x, f(x) = x^3, and f(x) = sin(x). Some examples of even functions include f(x) = x^2, f(x) = cos(x), and f(x) = |x|.

5. What are the properties of odd and even functions?

One property of odd functions is that the integral from -a to a is always equal to 0, where a is any real number. This is because the positive and negative areas of the function cancel each other out. One property of even functions is that the integral from -a to a is always equal to twice the integral from 0 to a. This is because the positive and negative areas of the function are equal and add together to give the total area. Additionally, the product of two odd functions is an even function, and the product of two even functions is an odd function.

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