Solve the following equation giving values for 0-360deg
cosA=cos2A+cos4A
cos2A=cos(30-A)
i probably missed something on the identities part.
thanks
Looking back at alexmahone's work:
If A is supposed to be between 0° and 360°, then 3A should be between 0° and 1080° (360° times 3). So from here you also have to mention that
$\displaystyle 3A=390^{\circ}$ and
$\displaystyle 3A=750^{\circ}$
because these angles are coterminal to 30° and they are between 0° and 1080°. Now divide both sides of both equations by 3 and you will get
$\displaystyle A=130^{\circ}$ and
$\displaystyle A=250^{\circ}$.
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