1. 8 = 8 => refrexive
2. If x = y, then y = x => symmetric
3. If x = y and y = 7, then x = 7 => transitive
4. 6 + 2 = 2 + 6 => commutative - addition
5. 5 ∙ 2 = 2 ∙ 5 => commutative - multiplication
6. 10 + (3 + 2) = (10 + 3) + 2 => associative - addition
7. 6(3 ∙ 5) = (6 ∙ 3)5 => associative - multiplication
8. 4(8 + 1) = 4 ∙ 8 + 4 ∙ 1 => distributive
9. 6 + 0 = 6 => identity - addition
10. 8 ∙ 1 = 8 => identity - multiplication
11. 1/2 ∙ 2 = 1 => multiplicative inverse
12. 5 ∙ 0 = 0 => property of zero
-y) = cos x cos y + sin x sin y becomes, in terms of sign,
cos(x-y) = (Note that cos(x-y) = cos x cos y + sin x sin y.
If angle x is in the fourth quadrant, then sin x is positive and cos x is negative.
If angle y is in the first quadrant, then sin y is positive and cos y is positive.
Then cos(x-y) becomes, in terms of sign:
(-)(+) + (+)(+), or
(-) + (+)
This would be positive, overall, if cos x cos y < sin x sin y.
The answer for this is answer A
