Answer:
Systematic error
Step-by-step explanation:
Assuming that none of the judges are biased, the most likely reason for this difference is the occurrence of systematic errors.
Systematic errors are errors introduced by inaccuracy in the experimental design, be it in the observation or measurement process.
In this case, the reaction time from observing the finish and stopping the clock for each judge might be different, which configures a systematic error.
Answer:

Step-by-step explanation:
Using the addition formulae for cosine
cos(x ± y) = cosxcosy ∓ sinxsiny
---------------------------------------------------------------
cos(120 + x) = cos120cosx - sin120sinx
= - cos60cosx - sin60sinx
= -
cosx -
sinx
squaring to obtain cos² (120 + x)
=
cos²x +
sinxcosx +
sin²x
--------------------------------------------------------------------
cos(120 - x) = cos120cosx + sin120sinx
= -cos60cosx + sin60sinx
= -
cosx +
sinx
squaring to obtain cos²(120 - x)
=
cos²x -
sinxcosx +
sin²x
--------------------------------------------------------------------------
Putting it all together
cos²x +
cos²x +
sinxcosx +
sin²x +
cos²x -
sinxcosx +
sin²x
= cos²x +
cos²x +
sin²x
=
cos²x +
sin²x
=
(cos²x + sin²x) = 
I think to N because it make more sense in the number line
C; terminating means it stops at a definite point
a is a repeating decimal, for b i think you mean radical of 10 and that’s irrational, and d is repeating