Math Problem Statement

find the area of the region enclosed by the curves y=sinx amd y=cos x on [0,pi/2]

Solution

To find the area of the region enclosed by the curves y=sin(x)y = \sin(x) and y=cos(x)y = \cos(x) on the interval [0,π2][0, \frac{\pi}{2}], follow these steps:

Step 1: Determine the Points of Intersection

Set sin(x)=cos(x)\sin(x) = \cos(x) to find the points where the curves intersect.

sin(x)=cos(x)\sin(x) = \cos(x)

Divide both sides by cos(x)\cos(x) (assuming cos(x)0\cos(x) \neq 0):

tan(x)=1\tan(x) = 1

The solution for xx within the interval [0,π2][0, \frac{\pi}{2}] is:

x=π4x = \frac{\pi}{4}

Step 2: Set Up the Integral

The area AA between two curves y=f(x)y = f(x) and y=g(x)y = g(x) from aa to bb is given by:

A=abf(x)g(x)dxA = \int_{a}^{b} \left| f(x) - g(x) \right| \, dx

For the interval [0,π4][0, \frac{\pi}{4}]:

A1=0π4(cos(x)sin(x))dxA_1 = \int_{0}^{\frac{\pi}{4}} (\cos(x) - \sin(x)) \, dx

For the interval [π4,π2][\frac{\pi}{4}, \frac{\pi}{2}]:

A2=π4π2(sin(x)cos(x))dxA_2 = \int_{\frac{\pi}{4}}^{\frac{\pi}{2}} (\sin(x) - \cos(x)) \, dx

Step 3: Compute the Integrals

A1=0π4(cos(x)sin(x))dx=[sin(x)+cos(x)]0π4A_1 = \int_{0}^{\frac{\pi}{4}} (\cos(x) - \sin(x)) \, dx = \left[\sin(x) + \cos(x)\right]_{0}^{\frac{\pi}{4}} =(sin(π4)+cos(π4))(sin(0)+cos(0))= \left(\sin\left(\frac{\pi}{4}\right) + \cos\left(\frac{\pi}{4}\right)\right) - \left(\sin(0) + \cos(0)\right) =(22+22)(0+1)=21= \left(\frac{\sqrt{2}}{2} + \frac{\sqrt{2}}{2}\right) - (0 + 1) = \sqrt{2} - 1

A2=π4π2(sin(x)cos(x))dx=[cos(x)sin(x)]π4π2A_2 = \int_{\frac{\pi}{4}}^{\frac{\pi}{2}} (\sin(x) - \cos(x)) \, dx = \left[-\cos(x) - \sin(x)\right]_{\frac{\pi}{4}}^{\frac{\pi}{2}} [ = \left[-\cos\left(\frac{\pi}{2}\right) - \sin\left(\frac{\pi}{2}\right)\right] - \left[-\cos\left(\frac{\pi}{4}\right) - \sin\left(\frac{\pi}{4}\right)\right] ] [ = \left[-0 - 1\right] - \left[-\frac{\sqrt{2}}{2} - \frac{\sqrt{2}}{2}\right] = -1 + \sqrt{2} ]

Step 4: Add the Two Areas Together

A=A1+A2=(21)+(21)=222A = A_1 + A_2 = (\sqrt{2} - 1) + (\sqrt{2} - 1) = 2\sqrt{2} - 2

Thus, the area of the region enclosed by the curves y=sin(x)y = \sin(x) and y=cos(x)y = \cos(x) on the interval [0,π2][0, \frac{\pi}{2}] is:

222\boxed{2\sqrt{2} - 2}

Would you like further details or have any questions?


Here are 5 related questions to explore:

  1. How would the area change if the interval was [0,π][0, \pi]?
  2. Can you find the area between y=sin(x)y = \sin(x) and y=cos(x)y = \cos(x) on [π2,π2][-\frac{\pi}{2}, \frac{\pi}{2}]?
  3. What happens to the area if we consider the interval [0,π/4][0, \pi/4] only?
  4. How do we calculate the area between y=sin(2x)y = \sin(2x) and y=cos(2x)y = \cos(2x) on [0,π2][0, \frac{\pi}{2}]?
  5. What if the curves were y=sin(x)y = \sin(x) and y=sin(2x)y = \sin(2x) on [0,π][0, \pi]?

Tip: When comparing areas under curves, always identify the points of intersection to correctly set up your integral limits.

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Math Problem Analysis

Mathematical Concepts

Calculus
Integration
Trigonometry

Formulas

Area between curves formula: A = ∫(f(x) - g(x)) dx

Theorems

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Suitable Grade Level

Advanced High School