O.533333333,basically 8 divide by 15
By Pythagoras AB^2 = 12^2 - 6^2 = 108
AB = sqrt 108 = 10.39 to nearest hundredth
The perpendicular from M to DC will be parallel and equal to AB so it = 10.39.
Also AB^2 = CB * DB
108 = 6 * DB
DB = 108/6 = 18
so DC = 18-6 = 12
MD^2 = (1/2*12)^2 + 108 = 144
so MD = 12
Given:
Measure of arc FJ = 84°
Measure of arc GH = 76°
To find:
The measure of angle HKJ.
Solution:
The image of the question is attached below.
Angles inside the circle theorem:
If two chords intersect inside a circle, then the measure of each angle is one half the sum of the measures of the intercepted arc and its vertical arc.




Sum of the adjacent angles in a straight line is 180°.
⇒ m∠GKH + m∠HKJ = 180°
⇒ 80° + m∠HKJ = 180°
Subtract 80° from both sides.
⇒ 80° + m∠HKJ - 80° = 180° - 80°
⇒ m∠HKJ = 100°
The measure of ∠HKJ is 100°.