Geometric Proofs= this time for real

Figure posted below at 3rd post.

1)In the figure above the measure of angle AME is x degrees, then the measure of angle EMB is 180-x degrees.

My answer is 1267200 inches

I don't know why I think this is the answer?I know a straight line is 180 degrees. This is a line adjacent to it.

2) If a central angle is 30 degrees, then the arc it defines is also 30 degrees.

My answer is Properties of a central angle. Because an arc is equal to central angle.

3) If a radius bisects a chord, then the lengths of the parts of the radius on either side of the chord are equal.

This proof is the definition of a radius. But why?

4) If a circle has a central point M, and both point A and point D are on the circle, then ls_MA and ls_MD will be equal.

This is a false proof. Therefore, unfounded?

5) The given points (4, -8), (4, -5), and (-2, -6) make a right triangle

This is also false proof. Does not make a right triangle. Making it an unfounded statement.

Please explain to me more on these subjects. Thanks.