You need to find out if 57 can be divided evenly by a number other than 1 and 57.
57 is odd, so it is not divisible by 2.
The digits of 57 are 5 and 7. Add 5 + 7 to get 12. Since 12 is divisible by 3 (12/3 = 4), then 57 is also divisible by 3.
57/3 = 19
19 is a prime number, so the only factors of 57 are 1, 3, 19, 57.
57 rows can be divided into 19 sections of 3 rows each or 3 sections of 19 rows each.
<u>Given</u>:
Given that we need to prove the identity 
<u>Proof</u>:
Step 1: Factor out the common term sin x, we get;

Step 2: Using the identity 

Step 3: Reciprocating sec x, we get;

Step 4: Splitting the denominator, we have;

Simplifying, we get;

Thus, the identity is proved.
To reduce a fraction divide the numerator and the denominator by their greatest common factor, GCF. ... The numerator and the denominator of the fraction are coprime numbers (no common prime factors, GCF = 1), the fraction cannot be reduced (simplified): irreducible fraction.
Given: C(N) = 15,000 + 8000N <span>
In the above equation simply substitute:
N(t) = 100t - 5t^2
for N
</span>
<span>Therefore:
C(t) = 15,000 + 8000{ 100t-5t^2 }
C(t) =15,000 + 800,000t - 40,000t^2.</span>
at t = 5
C(5) = 15,000 + 800,000*5
- 40,000*(5)^2
<span>C(5) = 3,015,000</span>