Q. The average value of csc2x over the interval from x=6π to x=4π is(A) π33(B) π3(C) π12(3−1)(D) 3(3−1)
Understand the problem: Understand the problem.We need to find the average value of the function csc2x over the interval [6π,4π]. The average value of a function f(x) over the interval [a,b] is given by the integral of f(x) from a to b, divided by the length of the interval (b−a).
Write down the formula: Write down the formula for the average value of a function.The average value of a function f(x) over the interval [a,b] is given by:Average value = (b−a)1∫abf(x)dx
Apply the formula to csc2x: Apply the formula to csc2x. For our function csc2x, a=6π and b=4π. So the average value is: Average value = (4π−6π)1×∫6π4πcsc2xdx
Calculate the length of the interval: Calculate the length of the interval.The length of the interval is π/4−π/6=(π/4)(3/3)−(π/6)(2/2)=(3π/12)−(2π/12)=π/12.
Set up the integral: Set up the integral.Now we have:Average value = (1/(π/12))×∫π/6π/4csc2xdxAverage value = (12/π)×∫π/6π/4csc2xdx
Evaluate the integral: Evaluate the integral.The integral of csc2x is −cot(x). So we need to evaluate −cot(x) from 6π to 4π.
Calculate the antiderivative at the bounds: Calculate the antiderivative at the bounds.−cot(4π)=−1 (since cot(4π)=1)−cot(6π)=−3 (since cot(6π)=3)
Find the difference of the antiderivative at the bounds: Find the difference of the antiderivative at the bounds.(−1)−(−3)=−1+3
Multiply by the factor from step 5: Multiply by the factor from step 5.Average value = (12/π)∗(−1+3)Average value = (12/π)∗3−(12/π)
Simplify the expression: Simplify the expression.The average value cannot be simplified further in terms of exact values. So, the average value of csc2x over the interval [6π,4π] is π12⋅3−π12.
More problems from Sin, cos, and tan of special angles