Answer:
AB = 1.4 or 7/5
Explanation:
(Excuse my rambling but I wanted to be sure of myself)
AD = 2(5/2) = 5
AD is a diameter.
any triangle in a circle with the hypotenuse as the diameter is a right triangle.
Draw a line from point A to point C.
ΔACD is a right triangle.
Solve for ∠CAD:
sin CAD = 3/5 = 0.6000
∠CAD = 36.87°
arc CD = 2 x 36.87° = 73.74°
arc BC = arc CD = 73.74°
arc DB = 147.48°
∠BAD = 1/2 (147.48°) = 73.74°
draw a line from point D to point B
ΔBAD is a right triangle.
cos 73.74° = AB/5
AB = 1.4