The Riemann sum for the area of the triangle is [tex]A = B\cdot \Sigma \left(1-\frac{h}{H} \right) \,\Delta h[/tex].
The integral that gives the area is [tex]A = B\left[ \int\limits^H_0\, dh -\frac{1}{H} \int\limits^H_0 {h} \, dh\right][/tex], where [tex]a = 0[/tex] and [tex]b = H[/tex]
The exact area of the region is 12 square units.
The Riemann sum of the triangle is described by the following formula:
[tex]A = \Sigma\, b(h) \Delta h[/tex] (1)
Where:
- [tex]b(h)[/tex] - Base of the rectangle.
- [tex]\Delta h[/tex] - Height of the rectangle.
- [tex]A[/tex] - Area of the rectangle.
Now we derive an expression for the base of the rectangle in terms of the base and height of the triangle:
[tex]\frac{b(h)}{B} = \frac{H-h}{H}[/tex]
[tex]\frac{b(h)}{B} = 1 -\frac{h}{H}[/tex] (2)
Where:
- [tex]B[/tex] - Base of the triangle.
- [tex]H[/tex] - Height of the triangle.
- [tex]h[/tex] - Position of the rectangle within the triangle.
By (2) in (1), we obtain a Riemann sum for the area of the triangle:
[tex]A = B\cdot \Sigma \left(1-\frac{h}{H} \right) \,\Delta h[/tex] (3)
The Riemann sum for the area of the triangle is [tex]A = B\cdot \Sigma \left(1-\frac{h}{H} \right) \,\Delta h[/tex].
The integral that gives the area of the triangle is based on (3):
[tex]A = B\left[ \int\limits^H_0\, dh -\frac{1}{H} \int\limits^H_0 {h} \, dh\right][/tex]
The integral that gives the area is [tex]A = B\left[ \int\limits^H_0\, dh -\frac{1}{H} \int\limits^H_0 {h} \, dh\right][/tex], where [tex]a = 0[/tex] and [tex]b = H[/tex].
Now we obtain the exact expression by integration:
[tex]A = B\cdot \left[(H-0)-\frac{1}{2\cdot H}\cdot (H^{2}-0^{2}) \right][/tex]
[tex]A = \frac{1}{2}\cdot B\cdot H[/tex]
If we know that [tex]B = 3[/tex], [tex]H = 8[/tex], [tex]a = 0[/tex] and [tex]b = H[/tex], then the exact area of the region is:
[tex]A = \frac{1}{2}\cdot (3)\cdot (8)[/tex]
[tex]A = 12[/tex]
The exact area of the region is 12 square units.
We kindly invite to check this question on area calculations by integrals: https://brainly.com/question/25412968