⇒cos3(8π)cos(2π−8π)+sin3(8π)sin(2π−8π)
⇒cos38πsin8π+sin38πcos8π
⇒sin8πcos8π(sin28π+cos28π)
⇒21sin4π
⇒221
The value of cos3(8π).cos(83π)+sin3(8π).sin(83π) is:
Held on 9 Jan 2020 · Verified 6 Jul 2026.
21
221
21
41
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