express as a function of a positive acute angle cos 213° is equal to A. cos33° B. -cos33° C. cos57° D. -cos57°?
回答 (3)
2017-05-10 1:19 am
cos(213°)
= cos(180° + 33°) …… cos(213°) is in Quadrant 3, and thus negative.
= -cos(33°)
The answer: B. -cos(33°)
= cos(180° + 33°) …… cos(213°) is in Quadrant 3, and thus negative.
= -cos(33°)
The answer: B. -cos(33°)
2017-05-10 1:16 am
Add or subtract 180
213-180 = 33
So -cos33
213-180 = 33
So -cos33
2017-05-10 1:12 am
B. -cos33°
收錄日期: 2021-05-01 20:54:42
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