Suppose the width of your index finger is 0.5 inches and the length of your arm is 30.5 inches. Based on these measurements, what will be the angular width (in degrees) of your index finder held at arm’s length?
I believe you are asking how many degrees does the width of your finger cover at arm's length....
30.5 inches x 2pi = circumference your arm would cover if rotated =191.637 inches
the width of your finger covers 0.5 inches of this
0.5 / 191.637 * 360 = .939 degrees