Similarly, (R_n = 14 + \frac6n) (check: (R_n = L_n + \Delta x (f(b)-f(a)))? (f(b)-f(a)=6,\ \Delta x \cdot 6 = \frac12n), but careful – compute:)

Numerically: (\sin(22.5^\circ) \approx 0.382683,\ \sin(67.5^\circ) \approx 0.923880), sum (\approx 1.306563)

Sum: (\sum_i=0^n-1 4 = 4n,\ \sum_i=0^n-1 \frac6in = \frac6n \cdot \fracn(n-1)2 = 3(n-1))