Trigonometry! #3
Geometry
Level
5
\(A \in \left(0,90^{\circ}\right)\). Let \( E = (\cos(3A) - \cos (9A))(\sin(9A) - \sin(3A))\). The smallest integral value (in degrees) of A for which E is negative equals
This problem is part of the set Trigonometry.
by
Omkar Kulkarni