Should be equal to. sorry if its incorrect, but that's what i would go with.
Answer:
cot(∅) = 
Step-by-step explanation:
tan ∅ and cot ∅ are inverse functions
therefore the inverse of
tan ∅ = √15 / 10
is equal to
cot ∅ = 10 / √15
Rationalizing the denominator
* 
cot ∅ = 
The average of 5, 7, 12, and 12, is (5 + 7 + 12 + 12)/4.
(5 + 7 + 12 + 12)/4 = 36/4 = 9.
The average is 9.