A B C D is a square and B C and C D are diameters of both red semicircles and the heart formed is inscribed in the blue circle and tangent to both red circles as shown above and the blue circle intersects the heart at vertex A of the square.
Let A c and A s be the areas of the blue circle and the square respectively.
If A s A c = ω α ( β + γ α ) π , where α , β , γ and ω are coprime positive integers, find α + β + γ + ω .
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Label the diagram as follows, and let the sides of the square be s and the radius of the blue circle be r .
By the properties of a square, E G = E B = E C = E H = 2 s , G A = 2 2 s , and ∠ E G F = 4 5 ° .
Then E F = H F − H E = r − 2 s and F G = F A − G A = r − 2 2 s .
By the law of cosines on △ E F G , E F 2 = E G 2 + F G 2 − 2 ⋅ E G ⋅ F G ⋅ cos ∠ E G F , or ( r − 2 s ) 2 = ( 2 s ) 2 + ( r − 2 2 s ) 2 − 2 ⋅ ( 2 s ) ⋅ ( r − 2 2 s ) ⋅ cos 4 5 ° , which solves to r = 7 2 + 3 2 s .
Therefore, A s A c = s 2 π r 2 = s 2 π ( 7 2 + 3 2 s ) 2 = 4 9 2 ( 1 1 + 6 2 ) π , so that α = 2 , β = 1 1 , γ = 6 , ω = 4 9 , and α + β + γ + ω = 6 8 .
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Using the diagram above and the law of cosines on △ C E F with included m ∠ E C F = 4 5 ∘ we have:
( r − 2 a ) 2 = ( 2 a − r ) 2 + 4 a 2 − 2 ( 2 a ) ( 2 2 a − r ) ⟹
4 r 2 − 4 a r + a 2 = 8 a 2 − 8 2 a r − 4 r 2 + a 2 − 2 2 a ( 2 a − r ) ⟹
− 4 a r = − 6 2 a r + 4 a 2 ⟹ 2 ( 3 2 − 2 ) a r = 4 a 2 ⟹ r = 7 3 2 + 2 a
⟹ A s A c = 4 9 ( 3 2 + 2 ) 2 π = 4 9 2 ( 1 1 + 6 2 ) π =
ω α ( β + γ α ) π ⟹ α + β + γ + ω = 6 8 .