Answer:
-0.391 < x < 0.391
Step-by-step explanation:
The Maclaurin series for cosine is:
cos(x) = ∑ (-1)ⁿ x²ⁿ / (2n)!
So the next term would be -x⁶/6!. When the absolute value of this is less than the error:
│-x⁶/6!│< 0.000005
x⁶ / 720 < 0.000005
x⁶ < 0.0036
-0.391 < x < 0.391
