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Sum of Sine Squares

Geometry Level 2

\[ \sin^2 18^ \circ + \sin ^2 30 ^ \circ. \]

Which of the following is equal to the above expression?

\[ \sin^2 42 ^ \circ \] \[ \sin^2 36 ^ \circ \] \[ \sin^2 48 ^ \circ \] \[ \sin^2 54 ^ \circ \]

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by Calvin Lin

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