The value of cos 3 π 8 . cos 3 π 8 + sin 3 π 8 . sin 3 π 8 is:

Question

The value of cos 3 π 8 . cos 3 π 8 + sin 3 π 8 . sin 3 π 8 is:, 1 2, 1 2 2, 1 2, 1 4

MARKS App · Accepted Answer

⇒ cos 3 π 8 cos π 2 - π 8 + sin 3 π 8 sin π 2 - π 8 ⇒ cos 3 π 8 sin π 8 + sin 3 π 8 cos π 8 ⇒ sin π 8 cos π 8 sin 2 π 8 + cos 2 π 8 ⇒ 1 2 sin π 4 ⇒ 1 2 2

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