Answer:
mDF = 90°
(Assuming arc mCE is 5x + 10)
Step-by-step explanation:
When we have two chords crossing in a circle, there is a property where the angle in the cross point is equal half the sum of the corresponding arcs.
So in this case, we have:
70° = (mCE + mDF)/2
Assuming mCE is 5x + 10, we have:
70 = (5x + 10 + 11x + 2)/2
70 = (16x + 12)/2
70 = 8x + 6
8x = 64
x = 8
So the arc mDF is:
mDF = 11x + 2 = 11 * 8 + 2 = 90°
