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Problem 231: (2018 AMC 12b, 25)
Circles $\omega_1$, $\omega_2$, and $\omega_3$ each have radius $4$ and are placed in the plane so that each circle is externally tangent to the other two. Points $P_1$, $P_2$, and $P_3$ lie on $\omega_1$, $\omega_2$, and $\omega_3$ respectively such that $P_1P_2=P_2P_3=P_3P_1$ and line $P_iP_{i+1}$ is tangent to $\omega_i$ for each $i=1,2,3$, where $P_4 = P_1$. See the figure below. The area of $\triangle P_1P_2P_3$ can be written in the form $\sqrt{a}+\sqrt{b}$ for positive integers $a$ and $b$. What is $a+b$? $\textbf{(A) }546\qquad$ $\textbf{(B) }548\qquad$ $\textbf{(C) }550\qquad$ $\textbf{(D) }552\qquad$ $\textbf{(E) }554$
Solution
Exercise 231: Solution
Circles $\omega_1,\omega_2,\omega_3$ each have radius $8$ and are placed in the plane so that each circle is externally tangent to the other two. Points $P_1,P_2,P_3$ lie on $\omega_1,\omega_2,\omega_3$, respectively, such that $P_1P_2=P_2P_3=P_3P_1$ and line $P_iP_{i+1}$ is tangent to $\omega_i$ for each $i=1,2,3$, where $P_4=P_1$. The area of $\triangle P_1P_2P_3$ can be written as $\sqrt a+\sqrt b$ for positive integers $a$ and $b$. What is $a+b$?
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