cos70= a) cos20
b)sin20
c)cos110
d)tan110?
回答 (2)
cos70°
= cos(90° - 20°)
= sin20°
...... The answer is: b) sin20°
sin(20). In a 20-70-90 triangle, the side "adjacent" to the 70 degree angle is "opposite" the 20 degree angle.
收錄日期: 2021-04-18 15:29:46
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