Solving Integrals with Semicircles: Proving $\frac{1}{2}\pi a^2$

  • Thread starter tandoorichicken
  • Start date
In summary, Today, Mr. Gishe assigned homework that involved finding the area of a semicircle using integration. The integral represents the area of the semicircle, which is equal to half of the circle's area. To find the area, one can either use the known formula for the area of a circle or use integration by substituting x=asinz.
  • #1
tandoorichicken
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I think Mr. Gishe went trigger happy when he was assigning homework today.

[tex] y=\sqrt{a^2-x^2} [/tex] where -a<=x<=a is a semicircle with r=a
show why [tex]\int_{-a}^{a} \sqrt{a^2-x^2}\,dx = \frac{1}{2} \pi a^2 [/tex]

(I think that's how its written)
 
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  • #2
What does the integral represent if the integrand is positive!? AREA!
What's the area of a half circle?
 
  • #3
It is given in the que it is a semi-circle
Do you know the area of circle
if yes then u can find the area of semicircle

or if u don't know n u want to calulate the integral

substitute
x=asinz
 

1. How do you solve integrals with semicircles?

To solve integrals with semicircles, we can use the formula for the area of a semicircle, which is A = 1/2 * pi * r^2. We can then substitute the radius r with an expression involving the variable x and solve the integral using standard techniques such as substitution or integration by parts.

2. What is the purpose of solving integrals with semicircles?

The purpose of solving integrals with semicircles is to determine the area under a semicircle curve, which can be useful in various applications such as calculating volumes or finding the center of mass for a semicircular object.

3. Can we use other shapes besides semicircles to solve integrals?

Yes, we can use other shapes such as triangles, rectangles, and trapezoids to solve integrals. The key is to find a formula for the area of the shape and then substitute the appropriate variables in the integral.

4. How do you prove the formula for the area of a semicircle, A = 1/2 * pi * r^2?

To prove the formula for the area of a semicircle, we can use the method of slicing the semicircle into infinitely thin slices and approximating the area of each slice with a rectangle. As the number of slices approaches infinity, the sum of the areas of the rectangles approaches the area of the semicircle. This can be expressed mathematically using calculus.

5. Are there any limitations to using semicircles to solve integrals?

One limitation is that this method only works for integrals where the region of integration is bounded by a semicircle. For integrals involving other shapes or curves, different methods may need to be used. Additionally, this method may not be the most efficient for solving certain integrals and may require additional steps compared to other techniques.

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