Use a double-angle identity to find the exact value. cos 105° sin 105°

Name: Use a double-angle identity to find the exact value. cos 105° sin 105°
Brand: Quizplus
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Question

Quizplus · Accepted Answer

Using the double-angle identity for sine: 
sin 2θ = 2sin θ cos θ

Let θ = 105°, then 
sin 210° = 2sin 105° cos 105°
-1 = 2sin 105° cos 105° 
cos 105° sin 105° = -1/2

Therefore, the answer is B, 11ea7f29_4ffb_305e_9ecd_6d7f4bdaf2db_TB3307_11.

Use a Double-Angle Identity to Find the Exact Value