cos' 15º-cos? 75º =
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Answered by
0
Step-by-step explanation:
cos '15° -cos ? 75 °= cos 60°
Answered by
1
Step-by-step explanation:
cos15°- cos75° =cos(45°-30°) - cos(45+30)
=(cos45°cos30°+sin45°sin30°)-(cos45°cos30-sin45°sin30°
=2sin45°sin30°
=2*1/root2 *1/2
= 1/root2
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