Answer: L = 29cm
Step-by-step explanation:
Let's go!!
To find any rectangle area, you have to apply this formula: A = L . w , where L is the length and w is the width.
So, we have w = L - 13 (the width is 13 less than the Length) and then, perimeter is 90 cm.
Well, I hope you remember that the perimeter of rectangle is 2L + 2W. In this case, 2L + 2w = 90
Then, you might to solve this system of equation:
2L + 2w = 90
w = L - 13
Simplifying the first equation, you'll have L + w = 45 (you can divide everything of 2).
Our new system:
L + w = 45
w = L - 13
Using the substituition method:
L + L - 13 = 45
2L = 58
L = 29 cm
the width is 29 - 13 = 16 cm
504+640=1144 hope this helps!
Answer:

Step-by-step explanation:
Given - The circumference of the ellipse approximated by
where 2a and 2b are the lengths of 2 the axes of the ellipse.
To find - Which equation is the result of solving the formula of the circumference for b ?
Solution -

Squaring Both sides, we get
![[\frac{C}{2\pi }]^{2} = [\sqrt{\frac{a^{2} + b^{2} }{2} }]^{2} \\\frac{C^{2} }{(2\pi)^{2} } = {\frac{a^{2} + b^{2} }{2} }\\2\frac{C^{2} }{4(\pi)^{2} } = {{a^{2} + b^{2} }](https://tex.z-dn.net/?f=%5B%5Cfrac%7BC%7D%7B2%5Cpi%20%7D%5D%5E%7B2%7D%20%20%20%3D%20%20%5B%5Csqrt%7B%5Cfrac%7Ba%5E%7B2%7D%20%2B%20b%5E%7B2%7D%20%7D%7B2%7D%20%7D%5D%5E%7B2%7D%20%5C%5C%5Cfrac%7BC%5E%7B2%7D%20%7D%7B%282%5Cpi%29%5E%7B2%7D%20%20%7D%20%20%20%3D%20%20%7B%5Cfrac%7Ba%5E%7B2%7D%20%2B%20b%5E%7B2%7D%20%7D%7B2%7D%20%7D%5C%5C2%5Cfrac%7BC%5E%7B2%7D%20%7D%7B4%28%5Cpi%29%5E%7B2%7D%20%20%7D%20%20%20%3D%20%20%7B%7Ba%5E%7B2%7D%20%2B%20b%5E%7B2%7D%20%7D)

∴ we get
