Tuesday, 14 August 2018

algebra precalculus - Evaluate this continued trigonometric sum


$$\sin^2(4) + \sin^2(8) + \sin^2(12) + ... + \sin^2(176)$$





Where the number is in degrees not radians.



$$\cos(x) = \sin(90 - x) \implies \cos(x) = \sin(90 + x)$$



$$\implies \sin(x) = \cos(x - 90)$$



$$S = \sum_{n=1}^{44} \sin^2(4n)$$

No comments:

Post a Comment

real analysis - How to find $lim_{hrightarrow 0}frac{sin(ha)}{h}$

How to find $\lim_{h\rightarrow 0}\frac{\sin(ha)}{h}$ without lhopital rule? I know when I use lhopital I easy get $$ \lim_{h\rightarrow 0}...