Answer:
Elgas is 9 years old.
Step-by-step explanation:
Alvin: 3 x Elgas
36: Alvin + Elgas
36 / 4 : 9
Elgas: 9
Alvin: 27
To check: 27 + 9= 36
When is cos (x) = 0? <em>at 90° (aka π/2)</em>
Answer: 
If you want to know the concept of square roots and cube roots ?
the square root of a number is that number which when multiplied by itself two times gives us that number
e.g.
√64 = x , so that (x)(x) = 64
and from our multiplication table we know that
(8)(8) = 64 , so that
√64 = 8
the cube root of a number is that number which when multiplied by itself three times gives us that number
e.g.
∛64 = x , so that (x)(x)(x) = 64 , and thus x = 4 because 4x4x4 = 64
so ∛64 = 4
