Slicing a Cylinder Revisited

Task.
From a cylinder with radius R = 3 in. and height H = 5 in., a vertical slice of thickness 1 in. was cut off, creating a rectangular opening. Design and construct from poster board such an "open" cylinder and compute its volume using vertical slices.

Can you compute the length of the remaining part of the circle that is the cylinder's base?

In our problem, b = 1 inch and r = 3 inches.
Using the Pythagorean theorem,
(1/2 chord)² + (r - b)² = r²
1/2 chord = √(r² - (r - b)²)

sin (A) = √(r2 - (r - b)2)/r

(SOH)

Solving for A,
A = sin^-1(√(r² - (r - b)²)/r)
Use the TI-83/84 to find A. From the home screen,

1→B
3→R
sin-1(√R2-(R-B)2/R)				ENTER
				48.1896851

Angle A is about 48 degrees.
The fractional part of the circumference of the circle that I removed is 2A/360. The whole circumference is 2*π*r.
So I removed 2*π*r*2A/360 = 5.046412023 inches of the circumference.
The whole circumference is 2πr =18.84955592 inches.
2πr - 5.0464120=13.8031439 inches. Now I can design my sliced cylinder .