Respuesta :
Answer:
29
Step-by-step explanation:
20^2 times 3.14= 1256
21^2 times 3.14= 1384.74
the sum of those two is 2640.74
the square root of that is 29
The radius of the circle is 29 cm.
We have the circle whose area is equal to the sum of the areas of two circles whose radii are 20cm & 21cm.
We have to find the radius of the circle.
Suppose you have to find the radius of a circle whose area is equal to the sum of the areas of two circles whose radii are r and R. How will you approach it?
Let the radius of the circle be x.
We know that the area of the circle is [tex]\pi r^{2}[/tex]. Then -
[tex]\pi x^{2} =\pi r^{2} +\pi R^{2} \\x=\sqrt{r^{2} + R^{2}} \\[/tex]
Now, in the question given to us -
r = 20cm and R = 21cm and 'x' denotes the radius of the circle we have to find.
Substituting the values in the above formula, we get -
x = [tex]\sqrt{400+441}[/tex]
x =29 cm
Hence, the radius of the circle is 29 cm.
To solve more problems on finding the area of circle, visit the link below -
https://brainly.com/question/16969543?referrer=searchResults
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