Let be the sum of the areas of and .
If , where and are coprime positive integers, find .
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x 2 + x y + y 2 = 7
x 2 − x y + y 2 = 5
The coefficient( x 2 ) = coefficient( y 2 ) = 1 ⟹ θ = 4 5 ∘ and the equations of rotation are :
x = 2 1 x ′ − 2 1 y ′
y = 2 1 x ′ + 2 1 y ′
Replacing ( x , y ) in the initial equations we obtain:
x ′ 2 + 3 y ′ 2 = 1 0
3 x ′ 2 + y ′ 2 = 1 4
Solving the above system we obtain x ′ = ± 2 (We only need x ′ here) and
y 2 ( x ′ ) = 1 4 − 3 x ′ 2 and y 1 ( x ′ ) = 3 1 0 − x ′ 2 ⟹ A 1 = ∫ − 2 2 y 2 ( x ′ ) − y 1 ( x ′ ) d x ′ = A 2 .
I 1 = ∫ − 2 2 y 2 ( x ′ ) d x ′ = ∫ − 2 2 1 4 − 3 x ′ 2 d x ′
Letting 3 x ′ = 1 4 sin ( θ ) ⟹ 3 d x ′ = 1 4 cos ( θ ) d θ ⟹
I 1 = 3 7 ( arcsin ( 1 4 3 x ′ ) + 1 4 3 x ′ 1 4 − 3 x ′ 2 ) ∣ − 2 2 = 3 1 4 ( arcsin ( 7 6 ) + 7 6 )
and
I 2 = ∫ − 2 2 y 1 ( x ′ ) d x ′ = 3 1 ∫ − 2 2 1 0 − x ′ 2 d x ′
Letting x ′ = 1 0 sin ( θ ) ⟹ d x ′ = 1 0 cos ( θ ) d θ ⟹
I 2 = 3 5 ( arcsin ( 1 0 x ′ ) + 1 0 x ′ 1 0 − x ′ 2 ) ∣ − 2 2 = 3 1 0 ( arcsin ( 5 2 ) + 5 6 )
⟹ A ! = I 1 − I 2 = 3 2 ( 7 arcsin ( 7 6 ) − 5 arcsin ( 5 2 ) ) = A 2
⟹ A = A 1 + A 2 = 3 4 ( 7 arcsin ( 7 6 ) − 5 arcsin ( 5 2 ) ) =
β α α ( λ arcsin ( λ ω ) − γ arcsin ( γ α ) ) ⟹ α + β + λ + ω + γ = 2 3