CEdward
RE: St1 - Why can't we just divide 2√2 to get the radius?
RE: Why do we need to know the angle that subtends the centers at 90 degrees
RE: Given all the work you did, how would you actually figure out the area of the common portion?
RE: St1 - Why can't we just divide 2√2 to get the radius?
Look at the attached figure. The sketch shows just 3 of the possible ways circles can be made when the distance between the centers is AB.
In the brown color circles, the radius will be AB/2, while in the blue colour circle, the radius is almost AB.RE: Why do we need to know the angle that subtends the centers at 90 degrees
This tells us that both circle have equal radius.RE: Given all the work you did, how would you actually figure out the area of the common portion?
Check the sketch on rightA(ACXD)= \(\frac{90}{360}*\pi r^2=\frac{1}{4}*\pi *2^2=\pi\)
Similarly for BCYD, A(BCYD)=\(\pi\)
Area of square ACBD = \(r^2=4\)
A(common portion)=\(2\pi - 4\)
Quote:
Why are the two circles have same radius, when the subtend same angle 90.
Join CD. ACD is a 45-45-90 triangle as AC=AD=r, and CAD is 90. CD =\(r_1\sqrt{2}\)....(I)
Now BCD is also 45-45-90 triangle for similar reasons. If radius is \(r_2\), then CD=\(r_2\sqrt{2}\)....(II)
Equate the two values of CD from I and II => \(r_1=r_2\)
Both radius are the same.
Harshjha001
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