3\sin 105^{\circ}+\cos 105^{\circ}=\cos 45^{\circ} – InterviewSolution

InterviewSolution

1.

3\sin 105^{\circ}+\cos 105^{\circ}=\cos 45^{\circ}

Answer»

Sin(60+45) + cos(60+45)

=[sin60cos45 +cos60sin45] + [cos60 cos45 - sin60sin45]

=cos 60 sin 45 +cos60 cos45

=1/2 * 1/√2 + 1/2 *1/√2

=1/√2

cos45

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