problem calculating factorials

[Iidrisu]

hi guys, i have a homework assigment that i have to complete but im a bit lost on how to do one part of it.

the part of the question im having trouble with is this "

Calculate sin^2(x) approximately by using n terms (n>0)
the Taylor series

sin(x)=Sum[(-1)^k x^(2k+1)/(2k+1)!] (k goes from 0 to n-1)

"
im not exactly sure how to evaluate the factorial in the equation. I know we should use a for loop but lets say i used
for(k=0;k<n;k++)
j=(2k+1)*j

that wont work because lets say n=3 it would say (1)*(3)*(5) ect. and not actually do (1)(2)(3)(4)(5).

[JosAH]

Suppose you have the k-th term of that Taylor series; express the k+1st term
in terms of the k-th term; note hat (2k+1)! == (2k-1)!*k*(k+1)

kind regards,

Jos

[Laharl]

n!, mathematically, is the product n(n-1)...(2)(1). Thus, (2k-1)!=(2k-1)(2k-2)...

To represent this in code, start by writing a loop to calculate n!, where n is any integer. A function is a good way to do this. Then, apply the function to your current problem.