Integrating factor of differential equation cos x dy/dx+y sin x = 1 is...
The given differential equation is:
cos(x) * dy/dx * y * sin(x) = 1
We can rewrite the equation as:
dy/dx = 1 / (y * cos(x) * sin(x))
Let's find the integrating factor for this differential equation:
Step 1: Identify the form of the differential equation
The given differential equation is not in standard form, but it can be transformed into a linear differential equation by multiplying both sides by cos(x) * sin(x):
cos(x) * sin(x) * dy/dx * y = 1 * cos(x) * sin(x)
This gives us the standard form of a linear differential equation:
dy/dx * y = cos(x) * sin(x)
Step 2: Identify the coefficient of y
The coefficient of y in the standard form is 1.
Step 3: Find the integrating factor
The integrating factor (IF) is given by the formula:
IF = exp ∫P(x) dx
Where P(x) is the coefficient of y.
In this case, P(x) = 1, so the integrating factor is:
IF = exp ∫1 dx
IF = exp(x)
Therefore, the integrating factor for the given differential equation is exp(x), or simply e^x.
Step 4: Multiply both sides of the differential equation by the integrating factor
Multiplying both sides of the differential equation by the integrating factor e^x, we get:
e^x * dy/dx * y = e^x * cos(x) * sin(x)
The left side of the equation can be written as the derivative of (e^x * y) with respect to x:
d/dx (e^x * y) = e^x * cos(x) * sin(x)
Step 5: Integrate both sides of the equation
Integrating both sides of the equation with respect to x, we get:
∫ d/dx (e^x * y) dx = ∫ e^x * cos(x) * sin(x) dx
e^x * y = ∫ e^x * cos(x) * sin(x) dx
Step 6: Solve for y
To solve for y, we divide both sides of the equation by e^x:
y = (∫ e^x * cos(x) * sin(x) dx) / e^x
Simplifying the integral and canceling out e^x, we get:
y = ∫ cos(x) * sin(x) dx
Using the trigonometric identity sin(2x) = 2sin(x)cos(x), we can rewrite the integral as:
y = ∫ (1/2) sin(2x) dx
Integrating, we get:
y = (-1/4) cos(2x) + C
Where C is the constant of integration.
Therefore, the solution to the given differential equation is:
y = (-1/4) cos(2x) + C
Conclusion:
The integrating factor of the given differential equation cos(x) * dy/dx * y * sin(x) = 1 is e^x.