A smaller circle touches a larger circle internally and passes through the center #O# of the larger circle. If the area of the smaller circle is #200 cm^2#, what is the area of the larger circle in #cm^2#?

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Answer 1 · 2016-11-30T16:37:22

#800#[#"cm"^2#]

The internal circle tangent to the external and containing the center of external circle, has as diameter the radius of the external.

Calling #r# radius of internal circle and
#R# radius of external circle,

#pi r^2=200# but as already said, #R = 2r# so
#pi R^2= pi(2r)^2=4pir^2=4 xx 200 = 800#