Which of the following would be best used as an electrical insulator?
a. copper
b. silver
c. salt water
d. wood

Explanation:

Wood when it is dry.

Silver Copper and Salt Water will always conduct electricity although Salt water is a little tricky. It depends on the amount of salt.

a is the best answer your welcome

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west