PART I
Angular size of the minor arc .
Half of the chord an the radius makes a right angled triangle with the radius as the hypotenuse and half of the chord as one of the shorter side.
Therefore, using trigonometric ratio, sine = opp/hyp
sine θ = 8/10 where θ is half the minor angle
θ = 53.13
Therefore, the angular size of the minor arc will be 53.13 × 2 = 106.26°
PART II
The length of an arc is given by (θ/360 )× 2πr
where θ is the angle subtended by the arc to the center of the circle and r is the radius of the circle.
Therefore, length = (106.26/360) × 3.142 × 2×10
= 18.548 Inches
