Answer:
k = 0.5
Step-by-step explanation:
A composite number has more than two factors.
(B) 21 is a composite number because the factors of 21 are 7 × 3.
The rule is minus 5.
So 20, 15, 10, 5, 0, -5
You can use the cosine rule for this - you might have to change some of the letters around for it to make sense though. Hope this helps!