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

Step-by-step explanation:
akajahsjallamamsjskdkldd
Y=5a-3b
Y=5(12)-3(4)
Y=60-12
Y=48
You don't have a sign between b and c in the equation, so I cannot help you with the last operation