ii) cos40° cos 100° cos160º = }
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Answered by
0
Answer:
cos40° cos 100° cos160º cos 220°
Answered by
1
Answer:
1/8
Step-by-step explanation:
cos40 cos 100 cos 160
= 1/2 * 2cos40 cos 100 cos 160
= 1/2 * (2cos160 cos 40) cos 100
= 1/2 * (cos 200 + cos 120 ) cos 100
= 1/4 * [ (2cos200 cos 100) + (2cos 120 cos 100) ]
= 1/4 *[ (cos 300 + cos 100) + 2*(-0.5)*cos100 ]
= 1/4 * cos 300
= 1/4 * cos 60
= 1/8
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