Chapter 5 - Section 5.2 - The Definite Integral - 5.2 Exercises - Page 388: 2

1.03319 The sum of the area of the 4 rectangles above the x-axis minus the sum of the 2 rectangles below the x-axis is the Riemann sum Graph shown below

Δx=$\frac{\frac{3\pi}{4} -0}{6} =\frac{\pi}{8} A=\frac{\pi}{8}$[Cos(0)+Cos($\frac{\pi}{8}$)+Cos($\frac{2\pi}{8}$)+Cos($\frac{3\pi}{8}$)+Cos($\frac{4\pi}{8}$)+Cos($\frac{5\pi}{8}$)] =1.03319