is an isosceles triangle with .
are infinitely many circles tangent to the triangle and to their neighboring circles.
Find the sum of areas of all these circles to 3 decimal places.
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2 × ∠ C Y O + ∠ C Z Y = 9 0 ∘
∠ C Y O = 2 1 × ( 9 0 ∘ − a r c t a n ( 4 1 ) ) = 3 7 . 9 8 1 8 8 ∘
r = 2 × t a n ( ∠ C Y O ) = 1 . 5 6 1 5 5
b = 8 − 2 r , b a = 8 2 , a = 4 8 − 2 r = 1 . 2 1 9 2 2
Area of trapezoid A B Y X is A t = 2 1 ( 4 + 2 a ) 2 R = 1 0 . 0 5 3 9
Area of the circle centered at O is A c = π r 2 = 7 . 6 6 0 6
The ratio of the areas A t A c = 0 . 7 6 1 9 4 8
This ratio remains the same for all the circles below as well, each within its own trapezoid, so the total area of circles is this ratio times the total area of △ X Y Z
A = 0 . 7 6 1 9 4 8 × 2 1 × 4 × 8 = 1 2 . 1 9 1 1 7