Answer:
Step-by-step explanation:
Given: 
To convert: the given sum into product
Solution:
Use formula: 
![cosx + cos3x + cos5x + cos7x=2\cos \left ( \frac{x+3x}{2} \right )\cos \left ( \frac{x-3x}{2} \right )+2\cos \left ( \frac{5x+7x}{2} \right )\cos \left ( \frac{5x-7x}{2} \right )\\=2\cos (2x)\cos (-x)+2\cos (6x)\cos (-x)\\=2\cos (2x)\cos (x)+2\cos (6x)\cos (x)\\=2\cos x\left [ \cos (2x)+\cos (6x) \right ]](https://tex.z-dn.net/?f=cosx%20%2B%20cos3x%20%2B%20cos5x%20%2B%20cos7x%3D2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx%2B3x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx-3x%7D%7B2%7D%20%5Cright%20%29%2B2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x%2B7x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x-7x%7D%7B2%7D%20%5Cright%20%29%5C%5C%3D2%5Ccos%20%282x%29%5Ccos%20%28-x%29%2B2%5Ccos%20%286x%29%5Ccos%20%28-x%29%5C%5C%3D2%5Ccos%20%282x%29%5Ccos%20%28x%29%2B2%5Ccos%20%286x%29%5Ccos%20%28x%29%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B%20%5Ccos%20%282x%29%2B%5Ccos%20%286x%29%20%5Cright%20%5D)
![cosx + cos3x + cos5x + cos7x=2\cos \left ( \frac{x+3x}{2} \right )\cos \left ( \frac{x-3x}{2} \right )+2\cos \left ( \frac{5x+7x}{2} \right )\cos \left ( \frac{5x-7x}{2} \right )\\=2\cos x\left [ \cos (2x)+\cos (6x) \right ]\\=2\cos x\left [2 \cos \left ( \frac{2x+6x}{2} \right )\cos \left ( \frac{2x-6x}{2} \right ) \right ]\\=2\cos x\left [ 2\cos (4x) \cos (-2x) \right ]\\=4\cos x\cos (4x)\cos (2x)](https://tex.z-dn.net/?f=cosx%20%2B%20cos3x%20%2B%20cos5x%20%2B%20cos7x%3D2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx%2B3x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7Bx-3x%7D%7B2%7D%20%5Cright%20%29%2B2%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x%2B7x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B5x-7x%7D%7B2%7D%20%5Cright%20%29%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B%20%5Ccos%20%282x%29%2B%5Ccos%20%286x%29%20%5Cright%20%5D%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B2%20%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B2x%2B6x%7D%7B2%7D%20%5Cright%20%29%5Ccos%20%5Cleft%20%28%20%5Cfrac%7B2x-6x%7D%7B2%7D%20%5Cright%20%29%20%5Cright%20%5D%5C%5C%3D2%5Ccos%20x%5Cleft%20%5B%202%5Ccos%20%284x%29%20%5Ccos%20%28-2x%29%20%5Cright%20%5D%5C%5C%3D4%5Ccos%20x%5Ccos%20%284x%29%5Ccos%20%282x%29)
If l=4w:
l=40, w = 10
40+40+10+10=100cm
anything bigger isn't allowed, so the width is 10cm
Now, we're assuming this is for interior angles.
the sum of all the interior angles in a polygon is
180(n - 2) n = number of sides in a polygon.
now, this is an OCTAgon, it has OCTA=8 sides, so it has a sum of its interior angles at 180( 8 - 2) --> 180(6) ---> 1080°.
now, we already know seven of those eight angles add up to 1000, so... surely you'd know what the last one is.
Answer:
? we dint know
Step-by-step explanation:
